DK45s low voltage at solenoid

billboe · May 27, 2018

hey all,

just went to start my dk45s and glow plugs came on fine but when i turned the key to crank the motor it just went dead. it may have made a bit of a strange sound, but, definitely didn't crank and the dash went black.

now when i turn the key i get nothing... no dash lights, no clicks, nothing at tall...

if i measure the at the battery terminals i get 12.87v (btw, battery is new as of last year)... if i keep the pos on the terminal and neg on the chassis i get around 8v. i cleaned where the neg attaches to the chassis (as well as both neg & pos terminals) and still get 8v. i also get 8v at the solenoid.

what appears to be interesting is that if i disconnect the main hot lead at the solenoid, i get the 12.87v between the pos terminal and chassis. after cleaning the large main connection at the solenoid and connecting it back together, i'm back to the 8v.

any advice on where to start to diagnose?

THANKS MUCH!

billboe

ritcheyvs · May 27, 2018

Probably high resistance in a battery cable or battery terminal connection. There is a history of these battery cables corroding inside the insulation (where you can't see it) creating high resistance. Sometimes just flexing the cable will improve the connection, temporarily. One way to troubleshoot is to bypass the battery cables (one at a time) with a jumper cable.

Fuddy1952 · May 27, 2018

ritcheyvs said:
Probably high resistance in a battery cable or battery terminal connection. There is a history of these battery cables corroding inside the insulation (where you can't see it) creating high resistance. Sometimes just flexing the cable will improve the connection, temporarily. One way to troubleshoot is to bypass the battery cables (one at a time) with a jumper cable.

Very good advice and that should show where problem is. If that's not it have the battery load tested, could be a bad new battery.

LouNY · May 27, 2018

Using your voltmeter, + lead on the battery +, - lead on the starter solenoid battery connection, crank and look at voltage reading;
should be 0 till cranking and then 1 or 2volts while cranking,
If that's good leave the + on battery and move the - lead to the starter power terminal;
not cranking should be battery voltage, cranking the same 1 or 2volts.
If bad to the solenoid cables or connections,
If bad to starter power connection, solenoid.

billboe · May 28, 2018

thanks ritcheyvs, i'll give the jumper cable tests a try. that said, i think the battery cables are ok. i got 12.87v between the disconnected + cable at the solenoid and chassis. it was only when i connected the + cable back to the solenoid did the voltage drop.

and LouNY, i don't get any cranking at all. maybe you just mean the key in the crank position, so, i'll try that as well.

thanks all!

ritcheyvs · May 28, 2018

LouNY meant to measure the voltage from one end of a battery cable to the other end of that same cable. That voltage should be zero (or almost zero) except then there is high current, like while cranking the starter. This is an excellent test if you have a way to connect both meter leads and watch the meter while turning the key switch. But most meter wires are too short and hard to fasten (hands off), which is why I didn't mention it.

ritcheyvs · May 28, 2018

billboe said:
... that said, i think the battery cables are ok. i got 12.87v between the disconnected + cable at the solenoid and chassis. it was only when i connected the + cable back to the solenoid did the voltage drop.

Actually, those measurements prove that the battery cable (or battery) is NOT OK. These measurements are nearly equivalent to the test LouNY proposed (unless the battery is bad). You basically proved there is a 4-5 volt drop (should be near zero) across the positive side battery cable caused by what should be a small current. If the key switch was off. it should be zero current unless you have the old-style stop solenoid (external linkage on right side of engine) which will may try to engage (for a several seconds) when you connect the cable to the starter solenoid.

billboe · May 28, 2018

ritcheyvs, you were right on! jumpering the neg battery cable fixed it. THANKS VERY MUCH!!!

now to find a compatible cable...

ritcheyvs · May 28, 2018

billboe said:
...now to find a compatible cable...

There is nothing special about the battery cable on a tractor. You should be able to get one at any auto parts store. Make sure the connectors will fit your battery terminal and screw terminal, the length is long enough, and the wire gauge is big enough. You have to remove the old cable anyway so you might want to take it with you to the store as a sample.