Farmall 70A - DTC 3157 (Resolved)

[klancf51]

Farmall 70A no start – ADIC (Analog Digital Instrument Cluster) displayed “Stop Sign” icon and DTC 3157. Also, once, briefly displayed DTC 14901. The tractor had been sitting outside for about 10 days.

DTC 3157 - ECU Not Detected on CAN bus.
DTC 14901 – ECU not present​

• We visually inspected the main wiring harness from the ECU back to the ADIC .
• We disconnected the wiring harness connectors from the ECU and re-connected them.
• We jump started the tractor successfully. After disconnecting the jumper cables, it ran for a few minutes and shut down with DTC 3157.
• We charged the battery. Again, it started and ran for a few minutes and shut down with DTC 3157.
• The next morning. we removed the battery, put it on the charger; meanwhile sprayed the grounding bolts in the battery compartment with brake cleaner and tightened them. Battery ground cable was not fully secure to frame and tightened ~ 1/8 turn. Re-installed the charged battery. Afterwards, tractor started and ran normally.

The reason we were suspicious of the battery and grounding is that for most ECU-related issues, the Farmall 70A Service Manual suggests “faulty supply voltage or ground, missing” as the #1 failure mode. The reason is that not all units on the CAN bus switch off communication at the same voltage level. This creates the situation where some components or control units are trying to communicate with switched-off units. Key takeaway: Always verify a properly charged battery and charging system as the first step in troubleshooting a CAN bus comms issue.

Btw, the DTC codes listed in the Farmall 70A Service Manual do not numerically correspond with those displayed on the ADIC. The Service Manual uses hexadecimal codes AND they don't convert directly to the DTCs on the ADIC. CASE IH should address this.

Update:
About 2 weeks later, DTC 3157 returned intermittently. Shortly after, the tractor would not crank intermittently and show a low battery voltage (~11.6 V) on the ADIC. When it would crank, the engine would start, but die seconds later. Sometimes it would start and run normally. Eventually, I was able to diagnose a fault in the ignition switch and replaced it. At the same time I replaced the ECU relay K-001 and the Cranking relay K-002. The ignition switch had failed - there is no doubt about that.

The unit is now starting & running "tip-top"; I would even say "like new". Displaying normal voltage (~12.6 V) consistently.

Note:

• The original ignition (#84280152) has been discontinued and the current part is #90414993.
• I replaced the OE Omron relays with sealed units.
• To replace the ignition switch, it isn't necessary to pull the steering wheel. However, it is necessary to remove the shuttle lever and hand throttle knob in order to lift the dash cowl enough to access the ignition switch.

Hope this helps!

 

[klancf51]

See Update above.

 

[MikeB22]

I had almost the same exact intermittent starting issue with my 70A. Although no codes were ever indicated. After testing and replacing some of the safety start switches and seeming to start and run most of the time, It stopped one day and became a permanent no-start. At this point it was easy to trouble-shoot. Traced it to the ignition relay #2 in the main fuse block.

Update, one year later 10/2025 similar intermittent no start issues reoccurred. Suspecting another relay issue I bought a relay tester tool. (Electronic Specialties relay buddy #190) and sure enough ignition relay #1 failed intermittently. Upon testing all the other relays, five others were bad. Obviously this is poor quality, defective manufacturing. I replaced all relays with NAPA / ECHLIN brand relays part #: ECH AR172 and have had no further issues.

Hope this helps

 

[MikeB22]

This is the relay tester

 

[klancf51]

I had almost the same exact intermittent starting issue with my 70A. Although no codes were ever indicated. After testing and replacing some of the safety start switches and seeming to start and run most of the time, It stopped one day and became a permanent no-start. At this point it was easy to trouble-shoot. Traced it to the ignition relay #2 in the main fuse block.

Update, one year later 10/2025 similar intermittent no start issues reoccurred. Suspecting another relay issue I bought a relay tester tool. (Electronic Specialties relay buddy #190) and sure enough ignition relay #1 failed intermittently. Upon testing all the other relays in the fuse box, five were defective. Obviously this is poor quality, defective manufacturing. I replaced all relays with NAPA / ECHLIN brand relays part #: ECH AR172 and have had no further issues.

Hope this helps

The OMRON G8V-RH-1C7T-R-12VDC (CNH #84561098- discontinued) are the OE relays on my unit. They were rated at 35A (continuous) and 90A (inrush) @12VDC on the N.O. contacts, electrical endurance 100,000 operations, not sealed (i.e. not washable). An aftermarket replacement should meet or exceed those ratings. I'm not certain about the various ratings for the superseding relay, CNH #87696396 except that 35A@12VDC appears to still be the continuous current rating.

ECH AR172 is rated for 20A@12VDC. That's a 57% continuous current de-rating. Just a heads up on that.

 

[MikeB22]

Thanks, good info. According to Echlin, when you do a cross-reference of the Omron part number it indicated the ECH AR172. That is why I went with those. I'll see how long these last and if needed, replace with the CaseIh 87696396 or perhaps the NAPA AR533 that are 25Amp. I was just leary of ordering from Case, fearing I would get more of the Omron junk. What did you use as an Omron replacement?

 

[klancf51]

Thanks, good info. According to Echlin, when you do a cross-reference of the Omron part number it indicated the ECH AR172. That is why I went with those. I'll see how long these last and if needed, replace with the CaseIh 87696396 or perhaps the NAPA AR533 that are 25Amp. I was just leary of ordering from Case, fearing I would get more of the Omron junk. What did you use as an Omron replacement?

The life expectancy is largely dependent on voltage and the characteristics of the electrical load. Environment plays in this too. Per the OMRON G8V-RH datasheet, the contacts are rated for 12VDC, but with engine running the normal voltage is 13.7 - 14.7 VDC. Just saying...

After reviewing the datasheets of several ISO 280 type relays,
I selected 301-1C-S-R1-12VDC (datasheet attached). In addition to meeting the OMRON G8V-RH current ratings, I liked the 14 VDC load rating and that it was available for purchase in a sealed unit. It would not surprise me one bit if CNH #87696396 is a 301 family relay. Maybe someone knows?

 

[MikeB22]

Much appreciated. You really did your homework on this. Very impressive! So far the ECH AR172 that I installed over a year and 400 hours ago, is working fine. I will check back here occasionally with any updates. Thanks again for your wisdom!

 

[sequoyah101]

Farmall 70A no start – ADIC (Analog Digital Instrument Cluster) displayed “Stop Sign” icon and DTC 3157. Also, once, briefly displayed DTC 14901. The tractor had been sitting outside for about 10 days.

DTC 3157 - ECU Not Detected on CAN bus.
DTC 14901 – ECU not present​

• We visually inspected the main wiring harness from the ECU back to the ADIC .
• We disconnected the wiring harness connectors from the ECU and re-connected them.
• We jump started the tractor successfully. After disconnecting the jumper cables, it ran for a few minutes and shut down with DTC 3157.
• We charged the battery. Again, it started and ran for a few minutes and shut down with DTC 3157.
• The next morning. we removed the battery, put it on the charger; meanwhile sprayed the grounding bolts in the battery compartment with brake cleaner and tightened them. Battery ground cable was not fully secure to frame and tightened ~ 1/8 turn. Re-installed the charged battery. Afterwards, tractor started and ran normally.

The reason we were suspicious of the battery and grounding is that for most ECU-related issues, the Farmall 70A Service Manual suggests “faulty supply voltage or ground, missing” as the #1 failure mode. The reason is that not all units on the CAN bus switch off communication at the same voltage level. This creates the situation where some components or control units are trying to communicate with switched-off units. Key takeaway: Always verify a properly charged battery and charging system as the first step in troubleshooting a CAN bus comms issue.

Btw, the DTC codes listed in the Farmall 70A Service Manual do not numerically correspond with those displayed on the ADIC. The Service Manual uses hexadecimal codes AND they don't convert directly to the DTCs on the ADIC. CASE IH should address this.

Update:
About 2 weeks later, DTC 3157 returned intermittently. Shortly after, the tractor would not crank intermittently and show a low battery voltage (~11.6 V) on the ADIC. When it would crank, the engine would start, but die seconds later. Sometimes it would start and run normally. Eventually, I was able to diagnose a fault in the ignition switch and replaced it. At the same time I replaced the ECU relay K-001 and the Cranking relay K-002. The ignition switch had failed - there is no doubt about that.

The unit is now starting & running "tip-top"; I would even say "like new". Displaying normal voltage (~12.6 V) consistently.

Note:

• The original ignition (#84280152) has been discontinued and the current part is #90414993.
• I replaced the OE Omron relays with sealed units.
• To replace the ignition switch, it isn't necessary to pull the steering wheel. However, it is necessary to remove the shuttle lever and hand throttle knob in order to lift the dash cowl enough to access the ignition switch.

Hope this helps!

 

[sequoyah101]

I have a 50A. The other day I went out to take the trash cans to the front gate, it cranked and started and died and showed 3157. I figure it is the relay, maybe the switch. Hope it is the relay, I'll test and check then check the ground and of course the battery which I am pretty sure is strong.

The factory supplied relays on these tractors are horrible. I have replaced two for lights already.

My tractor has never spent one minute out in the weather when it was not being used and lives in a cat patrolled barn just like all my other tractors.

Relays do not belong on tractors and this machine has several of them.

I went over to my little 40+ year-old Yanmar/JD 750 and cranked it right up to go take the trash out.

My modern tractors worry me about when one of them becomes a yard ornament because it can no longer be fixed. Tracing wires is a nightmare. I do wish they would bring back the old designs. At least my larger tractors are pre-def, pre-ECM and pre-common rail and have no solenoids anywhere on them. They do have semi-digital instrument panels and the fuel gauges, temp gauges and such seem to have consistently intermittent wiring problmes. Looks like someone could build a tractor with wiring rugged enough to last the life of a tractor.

 

[klancf51]

I have a 50A. The other day I went out to take the trash cans to the front gate, it cranked and started and died and showed 3157. I figure it is the relay, maybe the switch. Hope it is the relay, I'll test and check then check the ground and of course the battery which I am pretty sure is strong.

The factory supplied relays on these tractors are horrible. I have replaced two for lights already.

My tractor has never spent one minute out in the weather when it was not being used and lives in a cat patrolled barn just like all my other tractors.

Relays do not belong on tractors and this machine has several of them.

I went over to my little 40+ year-old Yanmar/JD 750 and cranked it right up to go take the trash out.

My modern tractors worry me about when one of them becomes a yard ornament because it can no longer be fixed. Tracing wires is a nightmare. I do wish they would bring back the old designs. At least my larger tractors are pre-def, pre-ECM and pre-common rail and have no solenoids anywhere on them. They do have semi-digital instrument panels and the fuel gauges, temp gauges and such seem to have consistently intermittent wiring problmes. Looks like someone could build a tractor with wiring rugged enough to last the life of a tractor.

"Relays do not belong on tractors and this machine has several of them."

More than several, I count twelve OMRON G8V-RH-1C7T-R-DC12.

Initially I dismissed your assertion out-of-hand, but it bothered me: why does this seem to be an issue with these Farmalls? I've since decided to reconsider and took a deeper dive. In short, I now believe you could make a strong argument. Here's my finding:

These are ISO280 automotive relays. They've had, and have, broad application in automotive applications with a good service record. But these same relays are relatively newer to agricultural tractor applications, and certainly to CNH Farmall A (Workmaster). What I've found is that reliability is highly dependent on their correct usage in a specific application. Automotive relay makers called this "intrinsic reliability" versus "reliability of use".

"Usage" encompasses:

• Coil Input (e.g. voltage, coil temperature)
• Contact Output (e.g. voltage, load characteristics)
• Mounting Design (e.g. Installation Direction)
• Storage and Usage Environment (e.g. spacing, gases, dust, vibration/shock, ambient temperature, humidity)
• Relay Installation & Soldering

Relay makers provide guidelines and precautions to electrical engineers & designers which inform them of known factors that affect readiness, endurance and performance in use. For example, it's well known among electronics manufacturers that silicone (RTV) outgassing (i.e. that vinegar-like odor) can degrade electrolytic capacitors when it's applied to capacitors to secure them to PCBs. I was somewhat surprised to learn that relays should not be stored or used near silicone, sulfuric (SO2, H2S) or organic gases, as degradation of the contacts may occur. Wow. Are there organic gases in your barn? Is that a red silicone rubber gasket sealing the Farmall A fuse/relay boxes? Maybe mounting the relay boxes next to a radiator isn't ideal placement for relay coil ambient temperature considerations. Did you know that the Omron G8V-RH-1C7T-R-DC12 isn't recommended for tropical regions? I didn't (Omron recommends a using sealed relay). I also didn't know that the spacing interval between relays can affect the coils (thermally and magnetically). I'm just touching the surface, there's a lot going with relay usage.

It turns out that the responsibility to follow precautions falls to the automotive (tractor) manufacturer. It is the manufacturer who best understands the application and usage; they are advised to thoroughly test and observe all precautions, and take countermeasures to ensure the relay will have reliability of use. Manufacturers are advised to evaluate the relay life under actual conditions. We can't know how CNH evaluated the Omron GV8 in the Farmall A application. If they missed something(s), well, there are good, inexpensive ISO280 automotive relays available in the aftermarket AND they are easy to replace. I now am keeping several in stock. I do believe that relays are intrinsically reliable, and can be used on tractors with endurance that approaches the relay's specifications, but only if our manufacturers are diligent in, selection, design, application and testing (usage). If they are not willing or able to do this, our tractors aren't going to be as reliable as we expect, and we will be replacing failed relays. The good news is that forums like this can help us to deal with such issues.

Important: when replacing a plug-in relay, insertion/removal is always performed normal to the socket surface (plug straight in/out), never angle (tilt) the relay, contact failure and relay terminal bending may occur.

Thanks for your comment - I learned from it.

See picture: Is that discoloration on the top right hand (LOADER) relay case? What caused it?

 

[sequoyah101]

"Relays do not belong on tractors and this machine has several of them."

More than several, I count twelve OMRON G8V-RH-1C7T-R-DC12.

Initially I dismissed your assertion out-of-hand, but it bothered me: why does this seem to be an issue with these Farmalls? I've since decided to reconsider and took a deeper dive. In short, I now believe you could make a strong argument. Here's my finding:

These are ISO280 automotive relays. They've had, and have, broad application in automotive applications with a good service record. But these same relays are relatively newer to agricultural tractor applications, and certainly to CNH Farmall A (Workmaster). What I've found is that reliability is highly dependent on their correct usage in a specific application. Automotive relay makers called this "intrinsic reliability" versus "reliability of use".

"Usage" encompasses:

• Coil Input (e.g. voltage, coil temperature)
• Contact Output (e.g. voltage, load characteristics)
• Mounting Design (e.g. Installation Direction)
• Storage and Usage Environment (e.g. spacing, gases, dust, vibration/shock, ambient temperature, humidity)
• Relay Installation & Soldering

Relay makers provide guidelines and precautions to electrical engineers & designers which inform them of known factors that affect readiness, endurance and performance in use. For example, it's well known among electronics manufacturers that silicone (RTV) outgassing (i.e. that vinegar-like odor) can degrade electrolytic capacitors when it's applied to capacitors to secure them to PCBs. I was somewhat surprised to learn that relays should not be stored or used near silicone, sulfuric (SO2, H2S) or organic gases, as degradation of the contacts may occur. Wow. Are there organic gases in your barn? Is that a red silicone rubber gasket sealing the Farmall A fuse/relay boxes? Maybe mounting the relay boxes next to a radiator isn't ideal placement for relay coil ambient temperature considerations. Did you know that the Omron G8V-RH-1C7T-R-DC12 isn't recommended for tropical regions? I didn't (Omron recommends a using sealed relay). I also didn't know that the spacing interval between relays can affect the coils (thermally and magnetically). I'm just touching the surface, there's a lot going with relay usage.

It turns out that the responsibility to follow precautions falls to the automotive (tractor) manufacturer. It is the manufacturer who best understands the application and usage; they are advised to thoroughly test and observe all precautions, and take countermeasures to ensure the relay will have reliability of use. Manufacturers are advised to evaluate the relay life under actual conditions. We can't know how CNH evaluated the Omron GV8 in the Farmall A application. If they missed something(s), well, there are good, inexpensive ISO280 automotive relays available in the aftermarket AND they are easy to replace. I now am keeping several in stock. I do believe that relays are intrinsically reliable, and can be used on tractors with endurance that approaches the relay's specifications, but only if our manufacturers are diligent in, selection, design, application and testing (usage). If they are not willing or able to do this, our tractors aren't going to be as reliable as we expect, and we will be replacing failed relays. The good news is that forums like this can help us to deal with such issues.

Important: when replacing a plug-in relay, insertion/removal is always performed normal to the socket surface (plug straight in/out), never angle (tilt) the relay, contact failure and relay terminal bending may occur.

Thanks for your comment - I learned from it.

See picture: Is that discoloration on the top right hand (LOADER) relay case? What caused it?

I have a freind named Allen, you must be his doppelganger in habit at least. I usually get at least one detailed and well researched message from him each week. His current fascination is how and why Patton was chosen as military governor of Bavaria after the war.

I will confirm that the problem with starting was a relay and I replaced it. Problem solved. I also keep spares. This is the third relay I have replaced in the last nearly 700 hours and all within the last 100 hours of use so there may be a trend. Hour or age related I can't say which, the tractor is a 2018 model. One was for the low beam work lights that hardly ever get used, the other was for some other light and the other was the starter relay.

It hardly seems proper that these should fail so frequently does it? They are mounted horizontally of course and are in a sealed enclosure. I did check the contact and test the relay, it was bad. As for silicon out gassing from within the enclosure, I could not say. The location near the radiator does not seem especially hot since the fan is blowing away from the enclosures and should not push hot air across them at all.

My winter repair plans will turn into spring again owing to sickness and cold I did not want to get out in. Most of what I have to do is repacking hydraulic seals and replacing hoses, gas struts on hoods (I may just build some prop legs instead) along with the rebuild of the rear drive of the Kubota 3680 mower. I have threatened to buy an air conditioned cab tractor mower but may endure yet another summer. I mention this since there seems to always be something to fix whether you have old or new equipment.

Yes, the forum can be quite useful in many cases.

 

[sequoyah101]

"Relays do not belong on tractors and this machine has several of them."

More than several, I count twelve OMRON G8V-RH-1C7T-R-DC12.

Initially I dismissed your assertion out-of-hand, but it bothered me: why does this seem to be an issue with these Farmalls? I've since decided to reconsider and took a deeper dive. In short, I now believe you could make a strong argument. Here's my finding:

These are ISO280 automotive relays. They've had, and have, broad application in automotive applications with a good service record. But these same relays are relatively newer to agricultural tractor applications, and certainly to CNH Farmall A (Workmaster). What I've found is that reliability is highly dependent on their correct usage in a specific application. Automotive relay makers called this "intrinsic reliability" versus "reliability of use".

"Usage" encompasses:

• Coil Input (e.g. voltage, coil temperature)
• Contact Output (e.g. voltage, load characteristics)
• Mounting Design (e.g. Installation Direction)
• Storage and Usage Environment (e.g. spacing, gases, dust, vibration/shock, ambient temperature, humidity)
• Relay Installation & Soldering

Relay makers provide guidelines and precautions to electrical engineers & designers which inform them of known factors that affect readiness, endurance and performance in use. For example, it's well known among electronics manufacturers that silicone (RTV) outgassing (i.e. that vinegar-like odor) can degrade electrolytic capacitors when it's applied to capacitors to secure them to PCBs. I was somewhat surprised to learn that relays should not be stored or used near silicone, sulfuric (SO2, H2S) or organic gases, as degradation of the contacts may occur. Wow. Are there organic gases in your barn? Is that a red silicone rubber gasket sealing the Farmall A fuse/relay boxes? Maybe mounting the relay boxes next to a radiator isn't ideal placement for relay coil ambient temperature considerations. Did you know that the Omron G8V-RH-1C7T-R-DC12 isn't recommended for tropical regions? I didn't (Omron recommends a using sealed relay). I also didn't know that the spacing interval between relays can affect the coils (thermally and magnetically). I'm just touching the surface, there's a lot going with relay usage.

It turns out that the responsibility to follow precautions falls to the automotive (tractor) manufacturer. It is the manufacturer who best understands the application and usage; they are advised to thoroughly test and observe all precautions, and take countermeasures to ensure the relay will have reliability of use. Manufacturers are advised to evaluate the relay life under actual conditions. We can't know how CNH evaluated the Omron GV8 in the Farmall A application. If they missed something(s), well, there are good, inexpensive ISO280 automotive relays available in the aftermarket AND they are easy to replace. I now am keeping several in stock. I do believe that relays are intrinsically reliable, and can be used on tractors with endurance that approaches the relay's specifications, but only if our manufacturers are diligent in, selection, design, application and testing (usage). If they are not willing or able to do this, our tractors aren't going to be as reliable as we expect, and we will be replacing failed relays. The good news is that forums like this can help us to deal with such issues.

Important: when replacing a plug-in relay, insertion/removal is always performed normal to the socket surface (plug straight in/out), never angle (tilt) the relay, contact failure and relay terminal bending may occur.

Thanks for your comment - I learned from it.

See picture: Is that discoloration on the top right hand (LOADER) relay case? What caused it?

Just noticed the discoloration of the top right relay in the shape of the solenoid. I will check for that elsewhere but the one I replaced is setting on my desk and has no such pattern.

 

[klancf51]

I have a freind named Allen, you must be his doppelganger in habit at least. I usually get at least one detailed and well researched message from him each week. His current fascination is how and why Patton was chosen as military governor of Bavaria after the war.

I will confirm that the problem with starting was a relay and I replaced it. Problem solved. I also keep spares. This is the third relay I have replaced in the last nearly 700 hours and all within the last 100 hours of use so there may be a trend. Hour or age related I can't say which, the tractor is a 2018 model. One was for the low beam work lights that hardly ever get used, the other was for some other light and the other was the starter relay.

It hardly seems proper that these should fail so frequently does it? They are mounted horizontally of course and are in a sealed enclosure. I did check the contact and test the relay, it was bad. As for silicon out gassing from within the enclosure, I could not say. The location near the radiator does not seem especially hot since the fan is blowing away from the enclosures and should not push hot air across them at all.

My winter repair plans will turn into spring again owing to sickness and cold I did not want to get out in. Most of what I have to do is repacking hydraulic seals and replacing hoses, gas struts on hoods (I may just build some prop legs instead) along with the rebuild of the rear drive of the Kubota 3680 mower. I have threatened to buy an air conditioned cab tractor mower but may endure yet another summer. I mention this since there seems to always be something to fix whether you have old or new equipment.

Yes, the forum can be quite useful in many cases.

"This is the third relay I have replaced in the last nearly 700 hours and all within the last 100 hours of use so there may be a trend. Hour or age related I can't say which, the tractor is a 2018 model. One was for the low beam work lights that hardly ever get used, the other was for some other light and the other was the starter relay."

Filament lamp circuits are subject to turn on inrush current 6x to 11x steady state current. ALSO LED lamps due to low wattage (i.e. current draw). Both cause contact degradation.

Panasonic manufactures automotive relays. In their Automotive Relay Users Guide (attached) they discuss relay precautions and reliability. In the Reliability Measures section they present the well-known "Bathtub Curve" and in discussing the "Wear out failure period" they state:
"In the final stage of the product's service lifetime comes the wear out failure period, in which the life of the product expires due to wear or fatigue. Preventive maintenance is effective for this type of failure. The timing of a relay's wear out failure can be predicted with a certain accuracy from the past record of uses. The use of a relay is intended only in the accidental failure period, and this period virtually represents the service lifetime of the relay."

The key takeaway: Automotive relays are subject to preventive, and even predictive, maintenance. The Farmall Operator's Manual makes no statement regarding that. From what I've learned, every 5 years might be a reasonable maintenance replacement cycle. The parts pricing will be far less in the auto/truck aftermarket or with electronics distributors vs dealership.

 

[klancf51]

Some good related info here: WM60 No Start (DTC 3157) / Fixed