GP light: On once this morning, that's it... Need her today. Not the time!

[N.E fjord-by-fjord 2fiddy]

Went outside to start her 5 min ago. No block heater, since it was above 15F overnight... "wait" light came on first try, but seemed to go out quicker than usual... Cranked. Good crank power... No start. Almost as if the GP's only heated up half way? Key off... Key on... No wait light. No start. Stopped after 3 tries... Batteries ain't what they should be...

I didn't have time to read any tech articles... and don't now. Any help appreciated, as I need her up and running now.

I plugged the block heater in so that in the meantime she's getting warmer, not colder while I wait to hear advice...

 

[BDCarrillo]

If your plugs are out a shot of ether should get her going. Otherwise it sounds like the glowplug controller or relay bit it... you'd CAREFULLY have to jump the relay to get juice to the plugs.

 

[PwrSmoke]

Better to adjust your, "to plug or not to plug" to 30 degrees, not 15F. They like it better and it's better for the truck long term to start warm. Weak batteries effect you in the crank and the glow departments. You need full amperage to get the most heat out of the glow plugs. I would do three things: 1) get your battery house in order, 2) check your glow plugs (the test light trick) and replace any dead ones, 3) plug in your truck more often. Until you get things dialed in, I imagine you will be plugging her in every morning. That's probably your only answer. Half hour is good...usually. If you've run the batteries down, it's a little more problematic and could involve a jump or a charger... but the block heater is usually magic. 10W30 in the winter makes a big difference too.

 

[N.E fjord-by-fjord 2fiddy]

That's the thing... Plugs are fine. They worked great all the way up until yesterday... Then this morning, the light quits on me, and the "ticking" that my voltage indicator does when the GPC is working isn't happening... I did the GP's last year, but I didn't do the GPC. It's stock from '94 I think... Unfortunately I think my GPC decided to quit on me this particular morning...

Anybody know the part number for that GPC solenoid? Looks like I have time to look for one in my neighborhood, since I'm not going anywhere today... :/

 

[N.E fjord-by-fjord 2fiddy]

...and usually I use 20F as my "plug her in" breakover temp.... It was late, and I saw 15 on my phone for the weather, and thought "ahhhh, screw it... she'll start in the morning for sure. She probably would have too if that GPC didn't crap out.

Relay, not solenoid. My bad...

 

[IDIoit]

cant you use a jumper wire from the batt to the glowplugs to get them to heat?

 

[laserjock]

I would check and make sure it's the relay that's bad. I think if you turn your key on and ground the post teh white wire is one it should click and heat the plugs. The controller pulls that contact to ground to activate it I believe. Check and make sure you have power at key on to the Red/green wire (I think that's right) and then ground the post the small white wire is on.

You did away with the temp switch mod we worked up right? No legacy code there screwing you is there?

 

[laserjock]

If it's an emergency, you could jump the big posts on the relay with a heavy gauge wire but I don't recommend that unless you really know what you are doing. It's enough current to melt stuff if you aren't careful.

 

[Agnem]

A pair of jumper cables works good as an emergency contactor. Just hook it up to the big lugs on the GPC and connect the other ends together to energize the plugs. The failure you have is exactly what normally happens when one glow plug fails. Just use a test light to find your bad plug, replace it, and all will be good.

 

[N.E fjord-by-fjord 2fiddy]

Picking up a test light later today, along with a GP relay... How do i test the GPs? I could act all confident and say I know, but I'm not gonna... Not worth mucking it up. Also, when I test the GPs, if they're all good, which I think they are... That means the relay is the culprit, right?

Side note: it was warm yesterday, and I did something I never do. I went to a carwash and gave her an undercarriage hose down... Is there anything that could have gotten wet to cause this issue? Just wondering.

Laser... That mod is still in there... Hadn't ever failed, so I didn't suspect it... But to tell you the truth, the verdict on that was that the hassle wasn't worth the benefit... which was minimal... So I'm just going to take it out. No point in having another possible failure point added into an already sensitive system. How much you wanna bet it's that relay I put in there, and everything else is fine.

 

[N.E fjord-by-fjord 2fiddy]

Well, just removed mod. Back to stock and still a no go. At least it feels good to know my mod wasn't a problem, even though it was next to pointless unless you live in Florida. Up here it seems like you always need those GPs... -18F tonight. Good stuff.

 

[laserjock]

Told you above how to test the relay above. To test the glow plugs, pull the connector off, hook your test light to a battery positive and if it lights up when you touch the GP it's in theory good.

Worse case, do what Mel said and jump the two big posts on the relay with jumper cables. That's the same as using a push button so you don't want to burn them too long. There is NO failsafe by jumping the relay.

 

[N.E fjord-by-fjord 2fiddy]

thought so... thanks

 

[Zaggnutt]

Good luck, man. Keep us posted.

 

[N.E fjord-by-fjord 2fiddy]

Relay in the GPC is replaced... still no light, so I'm about to go out and test all the GP's. Figured I'd ask a preemptive question before the test. I expect what Agnem said to be true and one to be bad, but if they're all good, what is the next thing in the checklist that I should look at if I know my plugs and relay are both good?