Electrical issue, no power

ISPKI

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Hey guys, my 94 f250 7.3idi failed me tonight at work. Went to start it, glow plugs prime but made a clicky sizzly noise, didnt heat the engine enough to fire up. Tried to start it, cranked nice and fast as usual but just belched grey smoke with no sign of firing up. Tried to prime again, truck lost all power, wont crank.

Preface: I have a manual priming system that bypasses the controller, uses a momentary switch. I also have a massive 300A manually actuated solenoid that cuts power between the battery (+) and the starter relay on the pass side fender. That relay seems to function fine, however, after pressing the prime switch, I lost all power to the cab and starter, none of my lights turn on, nadda, the only thing that seems to get power is the 300A safety relay that I installed. I am guessing the starter relay is cooked, but it was late and I didnt have my multi meter on me. Any other suggests on what to look for? I checked fuses and they did not appear blown.
 
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nostrokes

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What's the point of the 300a solenoid? If there is power to it and not out of it then there is your issue.
 

ISPKI

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Battery connections are tight, clean, brand new.

The 300A solenoid cuts power to the truck. It is working. I installed it because there was a parasitic drain in my cab in a location that I could not access and havent had the time to rip apart the cab trying to find it.
 

ISPKI

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Hey guys, so I did some testing on the electrical. my power cutoff relay reads 12.68v when engaged. The starter relay has power input at the input post but has no power reading at output post. When I tested it this afternoon, the cab has power again, but, when I trigger my GP relay with the momentary switch, it just rapidly clicks for a couple seconds and then clicks slower and slower until I lose power completely.

I also tested power at a couple of the GP connectors, had a friend press the momentary switch for a couple seconds while I took power reading but the GP connector never showed any voltage which leads me to believe that the GP relay is toast.

As for a replacement, my local parts store has a "heavy Duty" version of the starter relay that looks identical to the relay on the Left in the attached image. This seems to be the factory style GP relay but could anyone confirm?

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Fixnstuff

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Sounds like at the time you experienced this failure that it's a failed glow plug controller relay = when the battery was quickly drained the secondary contacts (the high amperage part that connects the two large terminals) were stuck together inside the relay drawing full current from the batteries and being stuck it would not disconnect, very quickly draining the batteries, probably burning out at least 2-3 glow plugs, probably ALL of them if they are not Motorcraft/Beru ZD9 glow plugs.

That is what causes the clicking noises you hear = some burnt out glow plugs. The sizzling noise sounds like pitted out secondary contacts (the high current contacts) inside of the GP controller RELAY. Motorcraft/Beru ZD9s which are the only glow plugs you should be using can actually accommodate a GP controller relay failure like this and still be good but it sounds like whatever glow plugs you have in there didn't survive.

If the GP controller relay did stick you should be able to see the evidence of substantial overheating of the metal ribbon resister connected to the negative OUTPUT side of the GP controller relay. The current goes through that resister to the glow plugs. Rather than being a bright steel color it's going
to be discolored, brown or even look like it's been in a fire. If the original plastic cover was over the controller it will be burnt through/melted near the resistor.

There is a fair chance that the GP Controller itself is still good, but your electrical system related to it is messed up - it was messed up before this happened so I guess you'll eventually find out if the controller is still good if you try to fix it right.

From my truck in July 2017:
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To answer one of your questions, the correct GP controller relay is the brown one on the left in the photo you posted.

One of the probable causes for the GP Controller Relay failure in my truck was a bad Hood to Cowl Seal which allowed rainwater to fall into the vicinity of and on top of the controller cover and eventually the moisture got into the relay, probably from around the posts. This photo shows quite a lot of rust on the bottom side of the relay which tends to support the leaking cowl seal explanation. I'll cut that relay open today and post a photo of the inside.

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Will replacing the relay and glow plugs fix your main problem? MAYBE but only partly or MAYBE NOT.

1) Apparently there was a problem with the GP controller or more likely it's wiring or glow plugs and a bypass of that problem was attempted by installing a push button. There is only one right way to fix a solid state GP controller issue and that is to fix it the right way which is actually very simple so then you will have all of the advantages and benefits that the controller provides including reduced smoke and emissions during start and warm up. You can't duplicate what the controller does with a push button.

2) Apparently there was a new or continuing electrical problem AFTER the push button was installed so you installed a 300 Amp Relay to disconnect and isolate the electrical system and the electrical problem(s) from the batteries when you are finished driving the truck each time. That didn't fix the problems, it only shuts them off when you turn the key off and shut the truck down and it turns the problems back on again when you energize that relay and start the truck again.

Usually a problem that isn't fixed will lead to another problem, then another and so on... sometimes very expensive problems result because a simple problem was neglected. Apparently there was/is a short somewhere drawing down the batteries? So what does that lead to next? Burnt wires or components?

You can handle this however you want but I think the BEST solution is to install and wire the solid state gp controller as it was from the factory. I think that most people would be happiest with that set up.
 
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Thewespaul

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Wow that’s a long post, I skimmed it and I have to disagree on the clicking, it is not a sign of bad glowplugs that is the sound of your relay cycling, glowplugs won’t make that sound. You want to hear that clicking
 

ISPKI

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Fixnstuff, I appreciate the extensive post. It ended up being the relay that I had installed to cut power before the starter relay. The ZD9 GPS are all functioning fine, got the truck running yesterday. I believe the clicking of the gp relay was due to the cutoff relay overheating causing it to lose contact, which let's it cool and reconnect again.

Unfortunately, the individual I bought the trick from had taken the plastic cover off the gp relay allowing the throttle cable to sit across the contacts, which eventually frayed and shorted out a whole bunch of stuff. I have replace a significant amount of the electrical but there are a few lights that stay energized that I haven't been able to figure out, such as the WTS somehow being on all the time with no visible power supply.

The relay was rated for 150A continuous duty, appearently not really though.
 

Fixnstuff

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Wow that’s a long post, I skimmed it and I have to disagree on the clicking, it is not a sign of bad glowplugs that is the sound of your relay cycling, glowplugs won’t make that sound. You want to hear that clicking

Yeah, sorry that was so long (late at night- lack of concentration). Two or more bad glow plugs will certainly cause the solid state GP controller to cycle the relay before it can complete the initial glow cycle, cycling between closed and open relay with loud clicking so yes a relay clicking like that certain can be and usually is caused by some bad glow plugs. It's caused by the controller detecting an artificially higher 'combined resistance' due to plugs that are either burnt out creating infinite resistance for that plug or a partially burnt out plug reading much higher resistance than normal.

The controller has an internal computer circuit where a reference temperature (actually a resistance) is set each time the truck is started. That's the reference point from which it determines the length of the initial glow plugs "on" cycle. With one or more bad glow plugs, the controller detects that increased combined resistance as an engine that is up to temperature so it opens the relay but THEN it immediately detects a reference temperature (resistance) which indicates that the engine is COLD so it closes the relay to energize the glow plugs again and it will cycle back and forth like that until it has 8 good glow plugs which are necessary for the controller to work properly.

You are talking about the after-glow cycle and that's another matter of discussion that I'm going to skip right now.
 
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