L3240 won't start when cold... Help!

[200mph]

Having multiple new relays be faulty is very unlikely.

Let's verify a few things as you've done a great deal of testing and it needs to be in one location to make it easier to follow.

First off there are two circuits needed for the glow plugs to function. 1) The low side or control circuit is used to energize the magnetic coil inside the relay to throw the contacts for the High side circuit. The low side is controlled by the CPU which takes into account coolant temperature to adjust the GP on-time. 2) High side or the main power supply to the Glow Plugs. The high side gets it's power directly from the battery after passing through the 50 amp slow burn fuse. This wire goes to the relay socket directly.

Let's first verify the high side circuit is functioning correctly.
Remove the wire at the GP buss bar.
Remove the Relay and jump the terminals with the black/red tracer (terminals 1 and 2).
Do you have battery voltage at the buss bar wire? Yes and this circuit is OK.

Low side.

Verify you have battery voltage at the Terminal 3 of the relay socket when the key is ON. (Meter: positive or red wire to terminal 3 and black wire to ground)
Do you have battery voltage?

Please confirm the results, even if you have to retest a few things.

Here to support.

 

[tthorkil]

Since you can jump across the relay socket with a wire and it works and from what I have interpreted from the conversation so far I believe that the problem may be the relay socket contact(s) for transferring the high current from the battery to the glow plugs. You mentioned discoloration on the spade of the original relay which could mean that there was a high resistance connection on one of the terminals which probably caused the contact to get overly hot and may have spread the contacts enough that the spade of the relay is no longer making a connection. When jumping across the relay if you inserted a wire into the relay socket it is most likely thicker than the relay spade and would make contact. I would closely inspect the relay socket for damage. Just another theory - good luck!

 

[bferris01]

Having multiple new relays be faulty is very unlikely.

Let's verify a few things as you've done a great deal of testing and it needs to be in one location to make it easier to follow.

First off there are two circuits needed for the glow plugs to function. 1) The low side or control circuit is used to energize the magnetic coil inside the relay to throw the contacts for the High side circuit. The low side is controlled by the CPU which takes into account coolant temperature to adjust the GP on-time. 2) High side or the main power supply to the Glow Plugs. The high side gets it's power directly from the battery after passing through the 50 amp slow burn fuse. This wire goes to the relay socket directly.

Let's first verify the high side circuit is functioning correctly.
Remove the wire at the GP buss bar.
Remove the Relay and jump the terminals with the black/red tracer (terminals 1 and 2).
Do you have battery voltage at the buss bar wire? Yes and this circuit is OK.

Low side.

Verify you have battery voltage at the Terminal 3 of the relay socket when the key is ON. (Meter: positive or red wire to terminal 3 and black wire to ground)
Do you have battery voltage?

Please confirm the results, even if you have to retest a few things.

Here to support.

Sir,

I just wet back out and verified, I do in fact have 12 volt to the wire going to the bus bar/glow plug when I jump the relay socket with a wire.

Also with the key on I have 12 volt at terminal #3

I did attempt to move/loosen the dash cluster to get better access to the relay sockets but it didn't provide me much more room, but best I can see all the spades look fine.

Just a note of thanks for the continued ideas.

 

[200mph]

When you say you jumped with a wire.... Was this just a bare wire or did it have male spade connectors? I was assuming you made a jumper wire as that is what I'd do. If using a bar wire Tthorkil might have a very valid point.


It would be nice if you can remove the terminals from inside the relay socket themselves and inspect first hand. Look for corrosion, poor fit with male connector or it could be they are inserted incorrectly. Sometime a small pin or screwdriver can be inserted to depress the locking tab on the wire terminal so it can be removed from the relay socket.


On the low side you have power to pin 3, so this leaves pin 4 and its associated wiring. I'd check this wire all the way back to the 20 pin instrument panel connector and focus on pin 11.

 

[bferris01]

When you say you jumped with a wire.... Was this just a bare wire or did it have male spade connectors? I was assuming you made a jumper wire as that is what I'd do. If using a bar wire Tthorkil might have a very valid point.


It would be nice if you can remove the terminals from inside the relay socket themselves and inspect first hand. Look for corrosion, poor fit with male connector or it could be they are inserted incorrectly. Sometime a small pin or screwdriver can be inserted to depress the locking tab on the wire terminal so it can be removed from the relay socket.


On the low side you have power to pin 3, so this leaves pin 4 and its associated wiring. I'd check this wire all the way back to the 20 pin instrument panel connector and focus on pin 11.

Yes, I just made it out of wire. I am back to work for the next 48 hours, so I will try again and see if I can get the relay socket off for a better look at the connections

I assumed pin 4 is ground? I will try and trace it back as well. Thanks again sir, have a great night.

 

[bferris01]

Hi Everyone,

Sorry I had to work 6 out of 7 days straight this week and that is 24 hour shifts, so I didn't have chance until today to get back.

I am unable to find any breaks in the wire so far.

I did make some "extender wires" with male and female spades to get the replay up out of the dash. Put male side in the relay socket and the female on the corresponding relay terminal so I could test.

Now that it is away from the other relay and I testing it with a meter, I am getting all the proper voltage to the relay (12V on terminal #1 always, 12volt on #2 with the key on.

But the relay is not clicking and passing 12 volt to terminal 3 like the other is. ( I tried all 3 relays I have an all act the same way. Also when I bench test them they click strong enough I can feel it )

Does anyone know if terminal 4 is just a ground or what it goes too?

I feel like something is not telling the relay that it is ok to activate and let the power through, maybe?????????

I don't know if any of that makes sense.....sorry.

I guess I will have to get it to the dealer somehow.

 

[bferris01]

Sorry for the delay again.

I did have a second to trouble shoot some more and found, when I ran another ground to the rely, it clicked, activated and was able to start in the cold like normal. So there is something a miss on the ground side that I need to track down.

Only has a short time before back to work, sorry this is becoming a long post.

 

[RickCf]

It does sound like a bad ground. With the hours you have you must be a firefighter.

 

[bferris01]

Yes, 5 more year until I can retire.

I am still tracing the ground no luck yet. I have run another ground to the relay and it works fine now until I can find the main cause and the wife will now be able to run it when I am working.

Thanks again everyone and have a happy and safe Christmas and New Year!

 

[200mph]

In the event you test your temperature sensor at coolant temperatures other than shown in the WSM, the equation below will help.

Enter the resistance value in Ohms and compare the calculated temperature with the known coolant temperature. Don't guess at the known temperature. It's best to measure it with another thermometer.

 

[Firefighterontheside]

I’m sitting here at the fire station reading this great post. I sure hope I can retire in five years, but most likely it will be ten. Working today and Christmas. Normally I work a 48.

I’m having similar trouble with my L4200. Hasn’t failed to start, but has struggled since it got colder. Haven’t tried in the very cold yet. I’m sure my glow plugs aren’t working. This thread may help me get mine fixed.

 

[200mph]

I might have figured out the problem, if your root cause is similar to what I found on my L4740-3.

Everything on my tractor checked out. 12 volts to relay control circuit. 12 volts to the power side of relay. Relay tests out measuring ohms and functions off tractor (mocked circuit using battery and lights). Verified Glow Plugs are functioning and all good (tested verifying ohms and also removed and test using battery to make certain they glow bright red). Also checked and cleaned to new metal all electrical joints/connections from battery to slow burn fuse and white connector under hood (cab models only?) and the buss bar to glow plugs. Even purchased new and verified good 40 amp relay. Starting would be very difficult when cold and never confident it would fire. If a jumper was ran from battery to white connector by oil filter that goes to the buss bar for 10 seconds or less it would start immediately under the same cold conditions. No amount of multiple GP cycles would allow it to start.

Only one place for the problem to be!!! Inside the glow plug relay connector.

It turns out the two female connectors for the power side of the relay (heavy gauge wire) had little to no interference fit with the male terminal. Took the housing apart and verified this was the issue. Before taking apart the housing, used a male terminal and inserted into each of the four terminals. The two terminals on the power side (large diameter wire) provided no grip while the other two (control side, small wire) gripped the male wire connector tightly. It's very easy to perform the test as one only needs a spare male wire terminal and to remove the relay from the housing.

Wire connectors are a special kind and not what you would normally will find locally. Modified the female connector to improve interference force using small pieces of a paper clip. Yes there might be better ways to fix, but I have limited time, its very cold outside and there is very limited space to work behind the instrument panel.

Given all the testing the OP has done. I would highly recommend looking at the two larger female connectors and see if there is ample force to make good electrical contact.

The relay always went in with some force, but this was due to the interference fit to the control side (small wires) of the relay. These grip really tight, but the larger ones were sloppy and provided little grip.

The power side female terminals are also larger (wider width) and would accept the bigger male terminals typically found on 60 amp relays.

It's a real pain to remove the relay connector from the metal support bar and then to take the two piece plastic housing apart and then remove the wire connector from the housing. This all needs to be done to access the wire connector.

I'm not crazy about the design of the female wire connector and think others might be experiencing the same problem. I'd love to find a replacement connector that would fit the stock housing.

If the modification to the female wiring connector doesn't work in the long run, I'll make a new relay harness and do away with the Kubota designed one.

Good luck to the OP and I hope this provides an area to investigate.

Added in Edit:
Since posting the original reply, I've documented what I found in the following post.

http://www.orangetractortalks.com/forums/showthread.php?t=40200&highlight=200mph

Hope this helps.