Glow plug relay? Or controller? Short cycle

[Blue Ox]

I don't have time to reread all if that to see what your exact symptoms were, but the glowplugs will short-cycle a few times after start and they will short-cycle after the wait light goes out if the engine isn't cranked. Hope that helps.

 

[Subourbon]

They were short cycling in a nblinking pattern even with the engine on
I tried to bypass the connector tonthe temperature sensor by unplugging the connector and putting a wire between the 2 "input" wire to the connector.
Same issue. I believe that rules out the temperature sensor, assuming I performed the test accurately.
Took apart the GP relay to clean it and test it.

I've got a simple powerfist 8347676 multimeter. Lowest ohm setting is 200.
It's weird because I got a negative value of -138 ohm at it's lowest with relay energized, then up (or down) to -199 ohms while it was blinking, and every value in between, but never lower than the -138
Once the relay is energized, I believe I'm supposed to have a near zero value. Don't quite understand the negative values but anyways, that's besides the point (I did try flipping my leads around but i got the 1 value, signifying infinite.
Also, I went to the audible continuity setting and have the beeping sound from the multimeter)

So my question is this now,

Could a relay still have the audible click, but yet still be considered bad?
As in, the electromagnet is energized but can't keep itself energized due to whatever could be wrong with it? Or not energized enough to keep the circuit closed.

Thanks again everyone, I am tempted to Fire the parts Canon like a user suggested, I jist want it to be the right part!

 

[Blue Ox]

You may do better to measure voltage on the solenoid with it energized. Something that experiences a lot of arcing like the contacts on a solenoid may not show continuity with the low amperage that a multi-meter can supply, but may still work with real current.

 

[Subourbon]

Will do that
Had to fix the water heater yesterday, cold showers are no fun.

Finally found the right terminology for meniscus though, I kept saying blinking.
Its relay chatter.
Thought it was weird that almost nobody on all the internet didn't have the same problem.
Dieselhub.com says that relay chatter coming from controller is almost always a faulty controller.
But I'm gonna test the relay, I believe the contact opening and closing like that made it very unhappy.
What kinda voltage can I expect across the relay to know if it's good or bad?

 

[Subourbon]

Meniscus? My issue***** holy frigging typo.

 

[Subourbon]

So I got my gf to turn the key to cycle the GPs while I had the multimeter on the relay terminals. Dropped to around 0.35v
I believe that's a pass.
So thay pretty well leaves the controller.
Or the temp sensor, if I ****** up the bypass test.

 

[mshawn]

If it's an original '82 he's going to have the earlier style controller/sensor with the divorced relay.

I have a couple of these kicking around if you need one.

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This is your problem!!!!! You could disconnect this an interrupt the power to and from and wire it online with a switch in the dash( a toggle) and turn it on went you need to start it . Also that plug that is broke off in there , if it falls down in the cylinder then pull the head . People will tell you to start it and it will blow out but that does not happen it just cause internal problem and you are looking at a complete rebuild or buying a new engine

 

[mshawn]

Hey guys n gals,

1982 k20 suburban 6.2 diesel automatic trans. Th400 with overdrive.

I've made this a bit of a long post because i crammed it with history and details, and questions, figured that would me get clearer answers than
Glow plugs no work, help.

So the glow plugs give me a hard time,
I changed 7 out of 8. The 8th one snapped in half coming out and the other part is still in there. Gonna have to get an easy out and get that guy out. But when driving, the glow plug light (GP) comes on. Weird, I thought it only comes on for the start and maybe the first few minutes of running to maintain a certain temperature when it's cold out.

But no, she's plenty warm enough, been running for a while and still, it comes on.
When it does come on, if I'm coasting or at a light, it's all good. If I press down on the accelerator, it's makes this infernal belt screeching racket. (Side note, I checked the belts, they're good, right, plenty of bite left). But when the GP goes out, back normal running (I have to lift off the accelerator, and back on it again otherwise the noise seems to continue).
That's really weird!
Fast forward to October 2021, driving along GP come on do their screeching noise, and light goes out, but the truck died on me. I dont know if it is related to the GP light issue, because it happened about 8 more times on my drive, GP light on and light off. I pulled over, park. Starts right up again, no fuss. So can't be the battery. (Not fuel either I was full, and it didn't sputter or hard start).

Fast forward again, I plugged it in (quebec winter are cold) and decided to give it a shake down, died on me again, started right back up. But then as I'm parking (backing into my driveway) the GP light flashes on n off like a turning blinker only faster, I hear the relay clunk clunk clunk (mounted on driver side fender, next too windshield washer bottle).
What is happening here! Then yesterday I decided to run it up again to see if it was intermittent. It cycled fine the first time, then when I tried to start, I had this weird sort of grinding noise, like maybe the starter gear turning, but solenoid not throwing it, so it's just doing nothing, turning in its housing instead of grabbing the flywheel.
It was very cold out though.
I gave the starter some light taps with the end of a broom handle to see if it was jammed, when I say light I mean light, I don't wanna break anything...

So to summarize
1. GP light comes in when engine running.
2. Screeching belt noise when GP light on, stops when GP goes off.
3. Engine dies, with or without GP light (fires right back up though)
4. Clunk clunk clunk like a blinker, GP relay acting up.
5. Starter grinding noise (I suspect it stays in it housing turning because there is no sign of life from the engine)

Questions:
Glow plugs shouldn't turn on when engine is warm at all, am I right?

Could the belt screeching noise be caused by the broken 8th glow plug I mentioned? They're AC delcos, just to mention that.

Could the GP electrical issue cause the engine to die? Sometimes when in park to warm it up a bit, I give the accelerator some taps (light) and it'll kill the engine too, start right back up. I know 6.2s are slow and gradual, and I shouldn't Rev jt at all in park.

Clunk clunk clunk, would that be a relay issue? Because I figured out that the GP relay is the piece on the fender, there's also the GP controller which is tucked between firewall and engine block (sort of behind the air cleaner area). Is this something that has happened to any of you, is the relay the issue or the controller? Evidence seems to be pointing at the relay from my findings... I hear it's not uncommon to replace either.

And lastly, would the clunking blinking GP relay lead to the starter not throwing? Since I believe the batteries divert power to the GPs upon turning the key , once their cycle is complete, then power goes to the starter motor for start up of the engine. 12v system.
Or is a proper cycle of the GPs necessary for starter to work properly, like a start permissive or "interlock" if you will. Because i dunno bout all that being around in the 80s.

Anyways, if you made it this far, I appreciate you taking the time to read. I did some youtubing to seenifnother reported the same issue but, seems to be very popular to put a manual GP switch instead of the stock OEM one, if you want to leave your thoughts on what you guys have and if its worth the switch, I'd love to hear your thoughts!

Thanks everyone,

Glow plug controller on the back of the drivers side head is bad . This will fix most of your problems. I would get the alternator check to see if this had damaged it. Grinding noise is a low voltage high amperage draw. All of this is caused by the controller pulling to ground. But I would check starter wires. The bad thing about these 6.2L diesels is one electrical problem can lead to it taking out a lot of other components. Get back to me if this doesn’t solve your problem. 1st change controller. 2nd catty alternator to have check for output, you could also have a builder to build it up to 185amp which is the high you can build that series of alternator, this will also make it a 1wire alternator. Low voltage high amp draw is a killer of these starters. Have it checked low voltage will lead to this starter to stay engaged even when you turn the key off after long crank periods. I have a battery quick disconnect added to mine just for this reason. Also check all engine to frame grounds. This should get you up and going. Again if not pm me and I’ll help you get it up and going