Help! L3240 won't start when cold

bferris01 · Dec 9, 2018

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.

RoyKing · Dec 9, 2018

From what you have describe you very close to figuring it out. So you got battery hot large terminal in , glow plugs large terminal out, you show plus 12v when you the key is on, and when glow plug on position half way to start, are you sure your hold the ignition in heat position and dash is showing the glow plug indicator right ? Now if the relay won't close it is the ground circuit through the ignition switch, verify with one more jumper from ground leg on the relay to known good ground it should fire the relay.

pepper66 · Dec 9, 2018

Terminal four is the ground that completes the relay coil circuit. I'm not sure if it goes through the ignition switch,or the instrument cluster. Maybe someone with a WSM could tell you. Don't ground that wire while it is connected to the tractor wiring. Leave it connected to the relay but disconnect from the connector side.

RoyKing · Dec 9, 2018

That's a good precaution. Then a way to verify it's bad use a bulb from battery to socket ground and turn key to heater and see if lights.

The Fred · Dec 10, 2018

At this point you might seek a little dealer or technical help. The wire that goes to the instrument cluster is the one that grounds the primary side of the glow plug relay.

If you put power to this side of the circuit chances are you will screw up the cluster itself as it most likely being 80s Jap technology isn't designed to withstand the current you apply.

Good luck, Fred

RoyKing · Dec 10, 2018

The Fred said:
At this point you might seek a little dealer or technical help. The wire that goes to the instrument cluster is the one that grounds the primary side of the glow plug relay.

If you put power to this side of the circuit chances are you will screw up the cluster itself as it most likely being 80s Jap technology isn't designed to withstand the current you apply.

Good luck, Fred

He is not putting any power into the cluster by grounding the relay to a known ground. He is bypassing the cut on side of the circuit. Since I don't have that model of tractor wiring diagram in front of me let me ask this question is this a manual heater circuit ? meaning do you have to hold the key between the on position and start for heater circuit to come on. Or is it an auto circuit that comes on when you turn the key to on and runs for 30 seconds.

moship · Dec 10, 2018

Pin 4 of the Glow Plug Relay is the ground side that goes back to the instrument panel. This is Pin 11 on the 20 pin connector on the instrument panel cluster. The OP can check continuity between the two ends (Pin 4 of relay and Pin 11 of connector). Should also check to make certain the pins are fully seated within their socket and verify there is no corrosion.

If all this checks out, it could be the coolant temperature sensor is not sending the correct ohm value with respect to temperature. IE: The computer thinks it is warmer than it really is.

I'm fairly certain I posted the info from the WSM on testing the coolant sensor, but it could be on the other forum the OP has been duplicating his efforts on.

Reg · Dec 10, 2018

Glow plugs DO deteriorate.
I went through the phases from harder starting when cold to harder starting when cool to wouldn't start unless the block heater had been plugged in for two hours if below freezing.

In retrospect I wasted a LOT of time, money and knuckle skin on lower hose and block heaters - - time money and effort that would have been better spent on troubleshooting the glow plugs themselves, which I had to do eventually anyway.

By the time I unhooked them so that I could meter them individually three were open circuit and one was 38 Ohms.

So, my recommendation is that you remove the wiring from each glow plug right at the glow plug, then meter the resistance of that glow plug to the engine block.
Anything over an Ohm or two is a BAD plug.
If this problem is new this season you likely only have ONE that is bad, but any that read significantly higher than the lowest two - - are at least "suspect".

The Fred · Dec 10, 2018

Reg said:
Glow plugs DO deteriorate.
I went through the phases from harder starting when cold to harder starting when cool to wouldn't start unless the block heater had been plugged in for two hours if below freezing.

In retrospect I wasted a LOT of time, money and knuckle skin on lower hose and block heaters - - time money and effort that would have been better spent on troubleshooting the glow plugs themselves, which I had to do eventually anyway.

By the time I unhooked them so that I could meter them individually three were open circuit and one was 38 Ohms.

So, my recommendation is that you remove the wiring from each glow plug right at the glow plug, then meter the resistance of that glow plug to the engine block.
Anything over an Ohm or two is a BAD plug.
If this problem is new this season you likely only have ONE that is bad, but any that read significantly higher than the lowest two - - are at least "suspect".

He's already proven the relay is not turning on so it's a moot point. I offered him the complete WSM for his machine but it's too large for email. That's why I asked him if he Skyped.

There is a whole troubleshooting process for the relay primary circuit.

Regards, Fred

crazyal · Dec 10, 2018

Do you want to fix it back to the way it left the factory (including the cost) or would you be fine with making a small modification? I think what I would do is just make it manual by removing the computer out of the system. You could simply add a push button style switch to activate the relay. It would be real cheap. You would even have a light on the dash to tell you how long to hold the button in for. Another option would be to add a block heater. My relay died and I didn't know because with the block heater the engine would start up anyway. If you know someone who knows electronics they could probably trace it down to the exact component that's bad. As for the water sensor vs the control board, does the yellow light stay on for a long time or does it shut right off? If it's staying on then the tractor knows it's cold and the glow plugs need to be on for longer.

For example years ago my oven died. It was just a year out of warranty. The heating element for the oven wasn't coming on. With a multi-meter I found that a $2 relay on the main control board was bad. The new board was something like $400 and it had already burnt up two heating elements so I wasn't about to give Maytag any more money. Chances are that there's a small relay soldered onto a board that closes to activate the larger relay. With some skills the dash could be troubleshot (assuming that you can get at the circuit board).