How to hotwire the glow-plugs

[Scrub]

I have a 86 with a 6.2 diesel (ya, I know) and it will start fine when mostly cool if the glowplugs come on. If I run it and get it warm enough for the glowplugs to decide they don't want to come on, the pot-licker won't start short of a 30 second grind contest on the starter motor. Is there a way to put a button on the glowplugs? OK it will have to be a high capacity button, but that's OK.

Thanks in advance

[jeffspower]

Scrap the high-amp button plan & use a FURRD (can't bear to use the correct spelling) starter solenoid. That way, your pushbutton is only carrying low amps to trigger the sol. I do this on customer's trucks quite often.

[79BIG10]

Here's a good link to show you how to do that. http://www.novaresource.org/starter.htm

[RockHQ]

Scrub said the problem with the engine is related to the glow plugs ie inability to start, but not to the starter ie inability to crank. There are a few different glow plug controllers and wiring used during the production run (1982-1993 for the 6.2). The general rule is the newer the better. If you have a 1985-1993 6.2 (i'm assuming a 1986 model) then the wiring for a glow plug override button is simple.

The glow plugs are energized by an electronical controller below 125 degrees Fahrenheit. The controller has a temperature inhibit switch wired to it which simply opens at around 125F. When the switch is open (non-conductive) an operational amplifier inside the controller inverts to ground, preventing glow plug operation.

To wire the manual switch, you simple need to put a jumper wire to override the temperature switch, allowing the controller to energize the glow plugs. You don't actually power up the glow plugs with the switch, so it needn't be capable of high current.

When you need to manually operate the glow plugs, turn the ignition off, then flip the switch you installed, and do a normal startup (pre-glow, crank, after-glow sequence).

The temperature switch is located at the rear of the right cylinder head next to the vacuum pump. It should have 2 wires going to it, these you will need to connect together (via the switch you'll install).

If you have more questions or you don't have an electronic controller (older style glow plug system) just ask me and i'll throw in more information.

-Axle

[arveetek]

Yep, follow Axle's advice regarding the temp. inhibit switch. GM installed this switch to prevent the glow plugs from cycling when the engine was warm. However, some diesels still need a glow period during that "lukewarm" stage when the engine isn't hot, nor is it cold. GM later did away with the switch.

You could also simply totally eliminate the inhibit switch by splicing the wires together located at the switch. This will allow the plugs to cycle every time the key is turned on.

And by the way, chin up! Owning a 6.2L diesel is a wonderful thing!

[Scrub]

WOW!

Thanks troops, That really makes it easy to accomplish the task.

The folks on this board are GREAT!

Thanks again

[Scrub]

OK,
I finaly got some time to do this, but I think maybe I have a different system. I don't see a vacuum pump.

I think I need to short the 2 wires with red arrows, which go to what looks like a heat sensor to me. The green arrow is one of the same wires. Sorry, it's not the best picture

Thanks

TW

[jeffspower]

NO! NO! not those! The green wires pictured go to the fast idle solenoid & cold start solenoid inside the injector pump. The red one is the fuel shutoff. You want the wires at the rear of the engine. The glow plug controller is at the rear of the driver's head on the top. The vac. pump is where the dist. is on a gas burner. The temp. inhibit switch is at the rear of the passenger side head to the rear of the exhaust manifold (usually).

[Scrub]

I feel like a Kompleat Edeyutt.

OK, I think I got it.

I guess I can either short the two wires, or put a switch between them,

Correct?

Thanks again.

[Scrub]

Hmm,
I put a switch in between the two wires in the last pic, and it didn't seem to do anything. I even pulled the connector and direct shorted the two wire and nothing happened. When I say nothing happened, I mean I drove to town and back and turned off the truck. I then did a restart and expected the glow plugs to activate. Narp.. same as before.

Any ideas?

Thank in advance

[Scrub]

TTT

[mike reeh]

This is probably not what you were looking for, but I say scour the junkyard for a duramax and throw that puppy in your truck.. oh the allison trans would be a nice upgrade too

good luck

mike

[RockHQ]

Have you made any progress with the truck yet?
Sometimes the controller becomes heat sensitive as it ages and might do just what's happening in your case. I'd get a new unit and see if it cures the problem. BTW, i could not find a decent picture of the controller but here's a drawing:
Glow controller