Where does the GP system get power from?

[chris142]

Having glow plug issues again. And since I'm too stupid to understand the wiring diagram I thought it would be better to ask here.

They don't work when cold but once it warms up and I shut it off they work when I go to start it again so it must be a bad connection that's working better when warm?

 

[madpogue]

What year truck?

 

[chris142]

One in my signature. 87

 

[biggun]

how do you know they dont work? you hitting them with a test light? in my 86 there is a purple wire that is the power wire in the GP Relay on the Pass Fender. I did the bypass like lots of folks do. I would hit them with a test light and see whats up.

 

[chris142]

When it's cool out the light does a 1/2 second blink and the truck won't start.once warmed up the light stays on 8-10 seconds and it starts right up

 

[icanfixall]

Power is from the fender mounted solenoid. Look for a yellow double wire crimped into one lug. Also look at the same engine wire harness plug that melts on the same yellow wire end. That plug can't handle the huge draw of power the plugs require when it gets dirty. Resistance builds up and the heat melts the plug. Some electrical fires have burned down trucks from this before too. Remember this is a hot all the time circuit as is the alternator and the starter. Many do not know this and end up arcing these circuits. Then you find out just how fast 200 amps melts tiny wires.

 

[biggun]

loose connection somewhere

 

[chris142]

I bypassed that connection last time.got a good crimp and solder there so it's not at that connection

 

[chris142]

Ya where? I gotta start somewhere

 

[biggun]

thats what it sounds like to me buddy, personally if i was in your shoes i would rig up a manual switch for the glow plugs and be done with it all together. that way you know when they are getting power and when they are not.

 

[IDIoit]

my glow plug controller is wired straight to the battery for the heavy lug.
and one wire for ignition on.

 

[chris142]

my glow plug controller is wired straight to the battery for the heavy lug.
and one wire for ignition on.

That's my plan.but I don't know which wire feeds it just yet.the yellow wires go into a loom and not directly to the battery.there are a slew of fusable links at the solenoid but I have no idea which feeds the system. Electrical is not my strong point!

 

[IDIoit]

in stock form those yellow wires go to another relay, then to the glow plug relay.
the first relay is connected to the battery.

I have an aftermarket wiring harness.

 

[OLDBULL8]

This might help you figure it out. Make sure the Black wire has a GOOD ground, check for rust and or corrosion where it's connected.

 

[chris142]

This might help you figure it out. Make sure the Black wire has a GOOD ground, check for rust and or corrosion where it's connected.

Where is it grounded at?