glow plug relay remote wire always live!!

[dt23400]

just as the title says guys. ive been looking all over the net and can not find anything about it. my relay works and my glow plugs r good. the remote wire for the relay is wired to a switch in the cab by the po. i never really worried about it as everything worked when that button was hit. but now im looking to put a remote start in and this will b a problem. i sat there for a few minutes with the key on and the remote wire stays live. which in return would keep that relay live and eventually burn the gps out. wts light goes out and everything. what controls that remote wire? what do i do to fix it? i cant find anything. any info would be great. thanks in advanced.

[woodnthings8]

The GPR is controlled by a ground. If the previous owner is controlling the GPR manually, they more than likely are controlling the ground circuit. Usually what you do is cut the wire from the PCM or tie it into a three position switch. This way the switch position controls the GPR. The relay has a coil in it, so when the ground is removed the 12V power will travel to the coil and will appear like it is always energized.

You have 4 posts on the GPR. The two large ones, and two small ones. The large post that is protected by a boot is hot (12V). Comes off the battery and carries lots of currant (amps) this is the one that drives the Glow Plugs. The second large post is the GP feed when the solenoid is grounded.

The two smaller posts are the control circuit. The forward one is the 12 v switched ignition feed. This will show 12V any time the key is on. The back one is the ground feed from the PCM. If the ground is applied via the PCM or remote switch it will read 0 volts. But once the ground is removed, it will read 12 volts. This is because the coil sends the voltage through it and out to the circuit.

Think of it this way. If you attach two wires to a lightbulb. One is power and one is ground. You always have the power wire hooked up to the power source and the ground is how you control your bulb. If you remove the ground wire off of the grounding point that ground wire will now show power in it. The reason is the power is still applied and the element in the bulb is now part of the circuit. Once the ground is applied again the element will now have resistance and will illuminate.

Check out this video I put together showing the GPR operation.

GPR operation - YouTube

GPR operation - YouTube

[dt23400]

Ok I understand that. So I went out and hooked the wire back up. Turned the key and had power to all 4 post. So shouldn't the none live small gauge wire loose voltage after the wts light shuts off? If so mine doesn't.

[NoRalPh]

Realize though, the WTS light and the GPR have No Connection. That is, the PCM times-out the WTS yet keeps the GPs on for a Much longer time (0-120secs)

And I say "0" because when your engine is Hot, and you see the WTS, the GPs may not come on at All

Nice vid btw...

[dt23400]

so i need to use a volt meter rather than a standard on or off tester? because i left my key on for the gpr and the relay never shut off? how would i go about fixing the circut?

[dt23400]

so would i have to replace the pcm or can i fix the circuit somehow??

[belz]

Originally Posted by dt23400

Ok I understand that. So I went out and hooked the wire back up. Turned the key and had power to all 4 post. So shouldn't the none live small gauge wire loose voltage after the wts light shuts off? If so mine doesn't.

Well, in order for that relay to turn on one of the small wires needs to be + and the other - . So if all of them are + u should replace the relay. U may wanna disconnect the wires and test them.


Sent from my fone.

[NoRalPh]

Disconnect the two small wires. Determine which one is (+) with the key On,there can only Be one, put it aside for now (insulated).

Take your Test Light (I assume that's what you mean by an "on/off tester") and put the clip to the (+) on the battery and the probe on the Other sm wire. IF there is a Ground Path the bulb will light. This should NOT happen with the key OFF and only for a couple of mins with the key ON. If it's On longer than that, the PCM most likely has a problem...

[dt23400]

So if the PCM is a problem where doin go from there. Is it repairable?

[woodnthings8]

You have said that your GPR circuit is modified. If you want to return it to stock, you need to remove the switch and determine how the PO modified the circuit. Your PCM could be the issue, but asking on here about a specific modification done to your truck will not provide you the best answer. We can only guess what was done to your truck and how it was done.

Trace the wires at the switch and see if you can figure out what the PO did. That is your best bet really.