Confirmed wiring issue, engine won't crank over

[GXPWeasel]

Hi all.
This is a confirmed wiring issue.
Long story short (if you want the long version, check out my build thread) I installed the battery in my truck, and wired everything up where I "think" it should go. I am not 100% positive, because there are some spliced wires, cut wires, and overall shady work under the hood of my truck from the previous owners. I'm going back together with everything, and I've confirmed that the starter is good because the purple "start" wire was jumped straight to the battery, and the engine will crank. However, I'm not getting power through that wire when it is hooked up correctly, and I try to start the truck.

I have confirmed I'm getting power from the wires running off of the starter, all the way up to the main plug that goes into the firewall, from the engine compartment side. However from there it appears that there isn't any power getting into the cab. I've checked the fuses that are there, but none are blown. When I turn the key even to run, there are absolutely no lights on or anything inside the truck. I'm at a loss of what to check now.

Anyone have any ides of where I should start to look?

 

[Justins truck]

Yes, it sounds like a blown inline fusible link.

 

[Justins truck]

The original fusible leak used to come off of the starter solenoid main battery feed wire.... if blown it takes out power to everything. Not sure if you are working with original wiring or not ? It may of been cut out at onetime. Hope this may shed some light your way.

 

[GXPWeasel]

If that fusable link you're referencing was bad, would I have power all the way up to the firewall? Sounds to me like it would kill the power right there by the starter, and I wouldn't be getting 12V up to my power block, or to the plug going into the firewall.

I do believe that part of the wiring is original. It has a single 12ga (looks like it) wire that comes out only a few inches from the starter (big post, with the positive battery cable) and then goes to a 2 wire (also appear to be 12ga or maybe 14ga). Those run up to the main wiring bundle, after one of them goes to the alternator. It appears wired correctly according to the service manual / wiring diagrams that I've found for that year.

1982 GMC C1500, with a 305.

 

[Justins truck]

Yes your correct, I over read about having power to the junction block at the firewall, did you happen to separate the junction block at the fire wall then? if you have power on the engine side, then you should have power inside the cab at the junction block... I would suggest to separate the two halfs and see if you have rotted or burnt connections between the two halfs... let us know what you find here.

 

[GXPWeasel]

@Justins truck, no, I didn't separate those. I guess I didn't even know you could separate the junction block. I'll have to look up how to do that. I agree, it almost seems as though there is something wrong with that. Any pointers on how it removes? Mine is dirty, but it doesn't look damaged in any way. You can see from the picture below, in the upper LH side is what I referenced as the power block. There is 12v power to it, and coming back out (even on that cut red wire you can barely see). Then in the lower RH side of this same picture, is my junction block. It doesn't look terrible, but as I said, it's dirty. I didn't see how it came apart.

 

[Justins truck]

if you look into the center of the block yu will or should see a head of a bolt, loosen this fully and you should be able to pull the bulkhead halfs apart... with any luck you may find rotted pins or pins that have gone green!

 

[GXPWeasel]

Okay, I pulled apart the bulkhead wiring today. It was greasy / grimy, but not bad. I saw maybe a little green corrosion on the main 12ga wire that comes into the bulkhead wiring bundle with 12 volts. It's a red wire. I cleaned all the wires and pins up, and even pulled that pin and made sure it was very clean. I then lubed up all the connections with some electrical connection grease, and plugged it all back in.
I now get a full 12.6 volts (exact same voltage as my battery) from the wire in the fuse panel labeled battery. I also have 12 volts for all of my lamps when I have the light switch turned on, so I know I'm getting power to my fuse block. However I'm still stumped because I have no lights on in the gauges when I turn the key. NOTHING. I don't know why not. Does the ignition switch that is located on top of the steering column control all of that wiring?

Back 2 years ago when I first got the truck, I had to replace the ignition key cylinder because I had to destroy it to get the truck into neutral, and so I could turn the steering wheel to get it loaded onto the trailer. Could I have un plugged something in that column when I replaced the ignition key cylinder that would cause the no power issue I'm having? Could the ignition switch being bad cause me to not have any visible power (brake or battery light on in the fuel gauge when the key is turned) inside the truck? I think that's the direction I'm going to go from here now anyway, is tear apart the column and check if I forgot to hook something up, or un-plugged something. I need a new blinker switch anyway. Then I think I'll go ahead and replace the ignition switch too, since I'll already be close to there, and they are pretty cheap.

What else am I missing? It just seems like I don't have any power in the truck at all.

 

[75gmck25]

The key cylinder has a gear on the end that turns a toothed rack, and then the rack pulls a rod up and down the column. On the end of that rod is the electrical part of the ignition switch, mounted low on the steering column. If the rack breaks/cracks or the rod gets out of adjustment, turning the key does not move the electrical switch correctly and you don’t get power.

This is the part you may need, but it might be slightly different for your year of truck. Most parts stores stock them, since it’s a common failure point.

Advance Auto Parts - Down for Maintenance

 

[GXPWeasel]

Thanks for the quick tip / lesson there Bruce. I agree that I may need this, and I know for a fact I need the turn signal switch, so I'm going to purchase both and get them coming. Might even get a Neutral Safety switch as well, but I don't think this is the issue (just to have one on hand).

I'm still concerned that this isn't going to fix my issue. It just seems like there is something else missing because I don't see/hear anything inside the truck at all when I turn on the key...not even trying to start the engine.

 

[scrap--metal]

If the rack breaks/cracks or the rod gets out of adjustment, turning the key does not move the electrical switch correctly and you don’t get power.

I agree with Bruce's assessment. I can't think of any other reason why you'd have power at the fuse block, but no power to accessories with the ignition on. If you previously destroyed the lock cylinder, its very possible that the ignition rack got cracked or broken as collateral damage.

While you're waiting for parts, you may be able to disconnect the ignition switch from the steering column and attempt to bypass it to confirm that the issue is in the ignition. I haven't reviewed wiring diagrams for a more specific suggestion, but it's an idea.

 

[GXPWeasel]

I also noticed while looking over the fuse block/panel under the dash, that from the GM service manual, it shows that slot 1 in the diagrams there are circuit breakers. I have no clue what those are, but I do NOT have one in the truck... Maybe that's my issue? Although when I look at the manual and then back to my fuse panel, it appears that if something were to be placed in that spot, there would only be one leg of the fuse/circuit breaker that would have a connection anyway because there isn't a female receptacle in the RH side leg where the fuse or circuit breaker would sit.

I also only have a single "ign" wire plugged into my fuse panel, where there are clearly spots for 3 separate wires. The diagram / picture I attached shows that also. I just don't know if what I have is correct.

I'll try to post a picture or diagram as to what I'm talking about.

 

[GXPWeasel]

I agree with Bruce's assessment. I can't think of any other reason why you'd have power at the fuse block, but no power to accessories with the ignition on. If you previously destroyed the lock cylinder, its very possible that the ignition rack got cracked or broken as collateral damage.

While you're waiting for parts, you may be able to disconnect the ignition switch from the steering column and attempt to bypass it to confirm that the issue is in the ignition. I haven't reviewed wiring diagrams for a more specific suggestion, but it's an idea.

That's a thought for sure. Although hopefully I have parts before I make it back over there. I usually only get there to work on the truck on the weekends. Although it is close enough to make a quick trip to drop off or pick up things if needed.

 

[GXPWeasel]

I wanted to update my thread wit what I found was wrong with the truck. After several hours of tracing wires under the dash, finding NOTHING wrong with any of them, or the switches (including the ignition switch) they went to, my dad and I were finally able to brainstorm for a bit, and we found my problem. It all went back to the power block (for lack of a better term) that was mounted on the firewall. We couldn't understand why there were so many cut wires there. After a bit of looking over the engine wiring schematics, and wire tracing, I connected 2 wires together that I "think" should have gone up to that power block from the factory. As soon as I did, I had the seatbelt buzzer going off in the cab. And wouldn't you know it, turn the key, and she turns over like a new engine should.
Unfortunately, I have the wiring under the dash to button back up and make look pretty, and the new turn signal switch to install yet, and I was running short on time. Below is a picture of what I'm referring to as the "power block" and my quick fix to ensure that I have the correct wires together. I'll make these a permanent fixture under the power block studs next time over there.

 

[Bextreme04]

I wanted to update my thread wit what I found was wrong with the truck. After several hours of tracing wires under the dash, finding NOTHING wrong with any of them, or the switches (including the ignition switch) they went to, my dad and I were finally able to brainstorm for a bit, and we found my problem. It all went back to the power block (for lack of a better term) that was mounted on the firewall. We couldn't understand why there were so many cut wires there. After a bit of looking over the engine wiring schematics, and wire tracing, I connected 2 wires together that I "think" should have gone up to that power block from the factory. As soon as I did, I had the seatbelt buzzer going off in the cab. And wouldn't you know it, turn the key, and she turns over like a new engine should.
Unfortunately, I have the wiring under the dash to button back up and make look pretty, and the new turn signal switch to install yet, and I was running short on time. Below is a picture of what I'm referring to as the "power block" and my quick fix to ensure that I have the correct wires together. I'll make these a permanent fixture under the power block studs next time over there.

One of those wires is the power coming up from the starter lug and should have a fusible link at the starter side. The other wire is the ignition power going into the cab and should have a fusible link at the power block. Get rid of the wire nut and connect them to the lug with correct heat shrunk connectors and the fusible link so they don't corrode or come loose in the future.