Bad news big repair

[LittleBill21]

there is a wiring diagram above, according to that diagram it should be a ground, not a 12v line. grounding it should cause the gp to come on regardless of the ecu is trying to do.

 

[bearthebruce]

there is a wiring diagram above, according to that diagram it should be a ground, not a 12v line.

Yep - missed the link in post #88. Sorry. Ground it is.. pin 37 of the ECU has to go to ground to turn on the relay.

The only temp sensor I saw was the engine cooling temp sensor. To spray the freeze spray, you would have to remove it from the radiator which means the hole in the radiator has to be plugged so all the coolant does not come out. I don't think that is gonna git er dun..

I'm not sure how to fool the coolant temp sensor into thinking the ambient is glow plug worthy... I'll think on that.

 

[Alan46]

302 posts and counting. It just shows how good this site is!

 

[WranglerX]

Well heck here goes;
View attachment 725057
Terminal layouts

The automotive ISO mini relays above are typically available in two types of pin layout designated Type A and Type B layouts. These layouts are shown on the two 5-pin relays below (pin 87a not present on 4 pin relays):

Terminal/Pin number	Connection
85	Coil
86	Coil
87	Normally Open (NO)
87a	Normally Closed (NC) - not present on 4 pin relays
30	Common connection to NO & NC terminals

Per what has been posted here it is a possibility that your ECM is providing the ground for the relay coil either T85 or T87.
One way to verify that would be a voltage check of the relay base with the key turned on check for voltage on T85 or T87 of the relay socket,
if you have voltage on either of those then the ECM is providing the ground for the coil.
While the relay is removed you can look for voltage on T30, T87 or (T87A not likely) if so the system is good to the relay.

Also you could disconnect the battery and using an ohm meter check from the relay(s) from T87 to the glow plugs for continuity,
it may be T30 but normally that would be battery power but I have seem T87 used for power and T30 to the powered device.

If your system does not have the ECM grounding the relay coil with one side of the relay coil having voltage present whenever the key is on,
then one of those terminal T85 or T86 should be going to ground.

This link has a lot of good information on relays;
Automotive Relay Guide | 12 Volt Planet

Have fun.

Suggest you check you use of "T87" in your text.... Don't you really mean "T86"...

 

[RickB]

Yep - missed the link in post #88. Sorry. Ground it is.. pin 37 of the ECU has to go to ground to turn on the relay.

The only temp sensor I saw was the engine cooling temp sensor. To spray the freeze spray, you would have to remove it from the radiator which means the hole in the radiator has to be plugged so all the coolant does not come out. I don't think that is gonna git er dun..

I'm not sure how to fool the coolant temp sensor into thinking the ambient is glow plug worthy... I'll think on that.

A judiciously placed resistor of the proper value.

 

[LouNY]

Suggest you check you use of "T87" in your text.... Don't you really mean "T86"...

Yes good catch,
I went back and edited it.
Thanks for catching it.

 

[LouNY]

On some tractors disconnecting the temperature sensor will put the intake heater into default which is the longest time,
some will also have two temperature sensors also one for indication and one for manifold heat.

 

[dpgood1]

Do you have full coverage? The tractor could catch fire "accidently".

 

[bearthebruce]

Would Hay Dude have a resistor laying around? I know I have lots of them.. because earlier in my life I made a living as a sparky... But Hay Dude admits its been awhile since he did electrical/electronic stuff.

Here is a typical temp sensor spec:
Coolant Temperature Sensor; Outline Of Coolant Temperature Sensor; Structure Of Coolant Temperature Sensor; Function Of Coolant Temperature Sensor - Kubota D1803-CR-E4 Workshop Manual [Page 133] | ManualsLib

You'll see that the coldest temps produce high resistance. To fake it, unplug the coolant temp sensor and the glow plug circuit ought to be active. Unplugged = the equivalent of -40C or some crazy value.

That should let you at least check that the relay is being pulled in.

 

[RickB]

Would Hay Dude have a resistor laying around? I know I have lots of them.. because earlier in my life I made a living as a sparky... But Hay Dude admits its been awhile since he did electrical/electronic stuff.

Here is a typical temp sensor spec:
Coolant Temperature Sensor; Outline Of Coolant Temperature Sensor; Structure Of Coolant Temperature Sensor; Function Of Coolant Temperature Sensor - Kubota D1803-CR-E4 Workshop Manual [Page 133] | ManualsLib

You'll see that the coldest temps produce high resistance. To fake it, unplug the coolant temp sensor and the glow plug circuit ought to be active. Unplugged = the equivalent of -40C or some crazy value.

That should let you at least check that the relay is being pulled in.

More likely to throw an open circuit fault code.