Glow Timer Blows 5A Fuse

[Gregster613]

I wanted to ask if anyone else has had issues with their glow timer malfunctioning (out of the blue)? I just replaced my combo switch, put it all back together, went to start it up and no go! I had no timer light, checked the fuse and it was blown. Put in fresh fuse and it blew instantly. I tore it back apart, unplugged my timer put another fuse into the slot. It held good while the timer was out of the system but blew as soon as I plugged the harness into the timer.

I "ASSUME" that means the timer went bad? I ordered a new timer and I'll know for sure once it gets here but I wondered if anyone else has had something like this happen to them? I'm not the sharpest with electrical issues and have not a clue how to trouble check the old timer? I do know that I get a constant 12V to one side of the fuse spot in the fuse block - all the time, even with switch off. I don't know if that's supposed to be so or not. I've never had issues with the glow system before. I've read about a lot of glow plug issues and am ready for that side of the troubles -- but the timer malfunctioning? Not so much!
If anyone has advice, I'm all ears!! Thanks Greg

 

[oldnslo]

Does the other side of the fuse connection show continuity to ground with the timer plugged in but fuse removed? If yes then something in the timer circuit has failed - shorted to ground which would cause the fuse to blow.

 

[garry1p]

replaced my combo switch, put it all back together,

If the glow timer was working OK before you replaced the combo switch I would suspect something other than the glow timer.
What is connected to the combo switch that could cause the problem?

 

[Gregster613]

Does the other side of the fuse connection show continuity to ground with the timer plugged in but fuse removed? If yes then something in the timer circuit has failed - shorted to ground which would cause the fuse to blow.

Oldnslo, Good question - I don't know, I'll do that type test tomorrow. Thanks for the thought/advice and I sure hope nothing in the circuit just went bad. I hate trying to trace out lines, etc., etc.

 

[Gregster613]

If the glow timer was working OK before you replaced the combo switch I would suspect something other than the glow timer.
What is connected to the combo switch that could cause the problem?

I know it worked the last time I started up the tractor. A lot of things are combined in the combo switch - horn, high & low lights, turn signals. Nothing with the glow system though. They all are working great with the new switch in place. Which is what stumped me. I put the dash all back together; tested the new switch to ensure all was working and thought great! Today I went to run the rig and found out the no go. I've ordered a new timer and when it arrives I'll find out if that was the issue or not. I just thought I'd ask if this had occurred to anyone else before. I do suspect it was just coincidence that it happened. Least that's what I hope!

 

[Jake99]

I "put the dash togheter", than i would look there first.i dont know your dash.
Timers can fail for sure, but my guess is wire that got pinched or something thats is touching a ground. That timer has a output to the glowplugs. Bypass the timer with a piece of wire.
If u can send us a photo of your timer we can assit in how to troubleshoot this further.

 

[Gregster613]

Does the other side of the fuse connection show continuity to ground with the timer plugged in but fuse removed? If yes then something in the timer circuit has failed - shorted to ground which would cause the fuse to blow.

Oldnslo, I got sidetracked moving some brick blocks for the wife, but I got to do the test you suggested and.......

no - (zero for continuity) but (yes to resistance). Meter showed .013 -- .016 from the other side of fuse to ground. The other side of fuse spot shows battery voltage which is high 12v. This test was done with the entire dash disassembled, everything unplugged, wires just hanging loosely, lower dash also entirely off, thus ignition switch unplugged and out of circuit. The only item/wire I reattached for the test was the glow timer relay plug. So I'm wondering whether that means the glow timer relay is bad?

I am aware that 273/293's were known to have shorted wires in the harness where it passes between chassis and frame but mine has no visible shorts! I also have NO wires pinched underneath or inside of the dash. All is as it is supposed to be except that my glow light/system does not seem to function.

The timer I'm looking at/holding in my hands looks just fine from the outside view of it. No melted spots, no visible looks of distress, it just appears to not be working and I don't know how to test it with my voltmeter. IE...I don't know it it should show continuity between any of the prongs or resistance or if anything at all. My manual doesn't show any means of troubleshooting this item. It shows how to troubleshoot several other switches, etc., etc. but not this one.

But, the manual also talks of a glow relay which I am unable to find anywhere in the system. I just find the glow timer.

It's probably the timer that is bad and when my replacement gets here I'll then know for sure. I was just trying to find out if anyone had troubleshot/tested their timers and how to do so. Vise just replacing to find out. Greg

 

[oldnslo]

.013-.016 ohms is basically a dead short to ground

Formula is E(volts) = I (amps)x R( ohms) or transposed volts/ohms = amps. 12 / .014 = 850 amps so Houston we have a problem..

 

[Gregster613]

.013-.016 ohms is basically a dead short to ground

Formula is E(volts) = I (amps)x R( ohms) or transposed volts/ohms = amps. 12 / .014 = 850 amps so Houston we have a problem..

Okay then, but, where would that short possibly be? Inside the timer is my hope, because the wires all appear to be intact and ok. If internal to the timer there shouldn't be /might not be any visible clues? That's my hope for now at least!

 

[Gregster613]

Okay then, but, where would that short possibly be? Inside the timer is my hope, because the wires all appear to be intact and ok. If internal to the timer there shouldn't be /might not be any visible clues? That's my hope for now at least!

I had edited to add but it appeared not to save so here again. I don't know much about voltmeter usage but I thought that when the ends were touched together set on ohms (upside down U) and it gave 0.0 reading that was = to a dead short? That's what I get when I do that. It shows a direct connection to each prob and = an open line?

If I get some other reading as I did, wouldn't that mean resistance of some sort? I told you oldnslo I don't fully understand the meter or what I'm supposed to be seeing?

I was attempting to determine if there was an internal short in the timer but don't really know how to to that. I've got a timer (a small black box with 6 male probes) and wanted a way to determine it was functional by testing probes for shorts between them but am way off in my thinking I guess. My manual shows no way to test the timer, so I guess replacement is the only way to test? Thanks for any more and all help given! Greg

 

[oldnslo]

I had edited to add but it appeared not to save so here again. I don't know much about voltmeter usage but I thought that when the ends were touched together set on ohms (upside down U) and it gave 0.0 reading that was = to a dead short? That's what I get when I do that. It shows a direct connection to each prob and = an open line?

You are correct in reading 0 is a dead short (open line)but in your case the .01 is very close to that

If I get some other reading as I did, wouldn't that mean resistance of some sort? I told you oldnslo I don't fully understand the meter or what I'm supposed to be seeing?

Using Ohms law of E = IR or R = E/I and load of 3 amps you should see around 4 ohms resistance. I just used 3 amps as an example.

I was attempting to determine if there was an internal short in the timer but don't really know how to to that. I've got a timer (a small black box with 6 male probes) and wanted a way to determine it was functional by testing probes for shorts between them but am way off in my thinking I guess. My manual shows no way to test the timer, so I guess replacement is the only way to test? Thanks for any more and all help given! Greg

From everything you have stated the problem would appear to be in the timer control.

Hopefully someone with more electrical knowledge will chime in.

 

[garry1p]

One last thing .
With the timer unplugged and you still get a low ohm reading I would suspect the problem is in the wiring between the timer and the fuse block.

 

[Gregster613]

From everything you have stated the problem would appear to be in the timer control.

"From everything you have stated the problem would appear to be in the timer control." Thanks oldnslo, that's what I'm hoping is the case for me. You have helped me feel far more comfortable with my non-electrical trained diagnosis, I will give results once my new timer gets here and I see if it is indeed the problem!!
I do find it perplexing that there seems to be no way to electrically test this darn timer though! I do believe there must be a way to do so but it is unknown to me -- for now at least. Perhaps once the new time gets here it may show some readings when I test it before putting it into service. Thanks for the time you took to coach me!

 

[Gregster613]

"From everything you have stated the problem would appear to be in the timer control." Thanks oldnslo, that's what I'm hoping is the case for me. You have helped me feel far more comfortable with my non-electrical trained diagnosis, I will give results once my new timer gets here and I see if it is indeed the problem!!
I do find it perplexing that there seems to be no way to electrically test this darn timer though! I do believe there must be a way to do so but it is unknown to me -- for now at least. Perhaps once the new time gets here it may show some readings when I test it before putting it into service. Thanks for the time you took to coach me!

Well that wasn't the problem! Darn! New timer does the exact same as the old one, blows the 5A fuse as soon as switch is turned to glow position.

Ken asked me if I'd changed the plugs and I said no, so then today I did that with great hopes - but no that wasn't a cure either! New glow plugs, new glow timer, What else could be causing this I wonder?

I have both upper and lower dashes off and see all the mess of wires stuffed in under the steering wheel but absolutely nothing looks chaffed, worn, or overly tired-out. I see that there are several big fat slow blow fuses in the mess also...but again nothing looks bad.

I am starting to wonder if it could be the ignition switch going bad? I wanted to take it out and test it if I could; so I tried to take mine out from the lower dash but it is being very stubborn and doesn't want to do what the manual says it's supposed to -- just pop out of the hole once the silver knob is unscrewed. Mine wants to stay in place and since I don't know if it is a possible fault I don't want to fight it and maybe break something.

On the fuse spot (where the fuse plugs in) in the panel, I get full battery voltage from one side of the fuse. From the other side I get 0.0 continuity to ground, which I believe shows a direct short? I cannot find any possible short to ground - but there must be something somewhere that's faulty! Am I missing something somewhere in the circuit? I just can't think of anything else to check?! I'm just stumped for now! Greg

 

[oldnslo]

What is connected to terminal that shows continuity to ground?

I may have miss understood and thought the wire or plug on the timer that connected to fuse was what showed continuity to ground.

 

[garry1p]

I tore it back apart, unplugged my timer put another fuse into the slot. It held good while the timer was out of the system but blew as soon as I plugged the harness into the timer.

Right now this is the best clue as to what's going on. Without a wiring diagram that will make the fix more difficult and since you can see no problems with the wiring the meter will have to be your eyes.

Your and oldnslo assumption the timer was bad was a logical one but if the above holds true you will need to know what else is in the harness since the timer is not the problem everything that that plugs in at the same time as the timer is suspect. If the only thing you plug in is the timer itself then the short is in the wire from the fuse to the timer.

Since the problem started with the combo switch I'm curious as to why you replaced the combo switch?

 

[Gregster613]

Right now this is the best clue as to what's going on. Without a wiring diagram that will make the fix more difficult and since you can see no problems with the wiring the meter will have to be your eyes.

Your and oldnslo assumption the timer was bad was a logical one but if the above holds true you will need to know what else is in the harness since the timer is not the problem everything that that plugs in at the same time as the timer is suspect. If the only thing you plug in is the timer itself then the short is in the wire from the fuse to the timer.

Since the problem started with the combo switch I'm curious as to why you replaced the combo switch?

garry1p, This is what I did just before this saga began. Started tractor up, drove outside of garage to put on my forks w/thumb to move some limbs. Found out my thumb diverter valve wouldn't work. Drove back inside to troubleshoot and fix my diverter which is wired (via an add a switch connection) to my 10A light circuit. Found a blown 10A fuse in the light circuit. Discovered that when my combo switch went to high beams the fuse blew. My horn is also in the combo switch and hasn't worked for years. I replaced the combo switch and viola horn/all lights worked again and so did my diverter. I put the entire top dash back together and that's when I discovered that my glow circuit was now not working. This is now where I'm now at troubleshooting the WHY?

New glow timer, new glow plugs, and still glow circuit shows a short from one side of fuse to ground and blows the fuse. I have the blown fuse out and one one side of the fuse slot I get full battery voltage -- but on the other side of the fuse slot I get a direct connection to ground when I use my ohm meter set on ohms. I get a 0.0 reading. This is when the wires to the timer are plugged back into the timer. All other items items under the dash are disconnected.

So that tells me that somewhere in that timer circuit is a problem but where to look for it is the mystery to me!

The main problem is the lack of area to fully check the harness circuit. They are really stuffed up under the steering column but all wires look just fine, The harness is not chaffed, scrapped, or anything I can visibly see. I do have a schematic but it's tiny and barely readable. I also find it difficult to believe a wire just suddenly broke!

 

[Gregster613]

What is connected to terminal that shows continuity to ground?

I may have miss understood and thought the wire or plug on the timer that connected to fuse was what showed continuity to ground.

oldnslo, New glow timer, new glow plugs, and still glow circuit shows a short from one side of fuse to ground and blows the fuse. So the timer and plugs are not the problem.

I have the blown fuse out -- and from one side of the empty fuse slot I get full battery voltage -- but on the other side of the empty fuse slot I get a direct connection to ground when I use my ohm meter set on ohms. I get a 0.0 reading. I believe I should not get any reading at all from that side?

This is when the wires to the timer are plugged back into the timer. All other items items under the dash are disconnected. I know this shows a short somewhere in the timer circuit but the mystery question is where to look to find it?

 

[garry1p]

what else is in the harness since the timer is not the problem everything that that plugs in at the same time as the timer is suspect

How many connectors has the timer plug have? Is the timer plug just for the timer OR are there other connections made at the same time.
I'm wondering if the fuse or connector is shared with something else like a relay.

 

[oldnslo]

This is when the wires to the timer are plugged back into the timer. All other items items under the dash are disconnected. I know this shows a short somewhere in the timer circuit but the mystery question is where to look to find it?

With timer completely disconnected Can you take your voltmeter and check continuity to see which wire or wires on the timer module show little to resistance between them? This might help determine what is causing the short.

Question for someone smarter than me on solid state timer is do these possibly require power to not show short to ground? I have run into this problem on some pressure switches where you could not get an accurate continuity test unpowered.