Little help with wiring please.

[dieselutheran2]

I have a couple of pics of my wiring harness replacement. I don't work with wiring very often, so I need some help. The wiring diagram makes it look like there should be two relays, one for the starter and one for the glow plug system. Is this correct? The relay on the fender is what was in there when I bought the truck, I just added the one next to the voltage regulator. What post do I connect to the battery, to ground, to the glow plug controller (purple wire) and where the heck do the other wires go? There is a wire that runs along the positive cable to/from the starter solenoid. Is that a ground or positive line? Does the little metal cylinder get attached to ground on the fender or not at all? There is a black wire that looks to have a ground connector on the end, can I run that directly to the battery negative post? Also, on the drivers side under the brake master cyl, there are a couple of connections that don't seem to go anywhere, one with a blue connection and the other has two brown lines that come together in a brown female spade connector. Like I said, need a "little" help.

 

[The Warden]

Okay, let me see what I can do. Based on your pictures, I'm going to assume that your truck is an '83-'86. If it's an '87-'94, the wiring is different...if this is the case, disregard my post.

The wiring diagram makes it look like there should be two relays, one for the starter and one for the glow plug system. Is this correct? The relay on the fender is what was in there when I bought the truck, I just added the one next to the voltage regulator.

This is correct. The relay on the fender is the starter relay; the one next to the voltage regulator is the glow plug relay.

What post do I connect to the battery, to ground, to the glow plug controller (purple wire) and where the heck do the other wires go?

The wire from the battery should go onto one of the big terminals; the wires going to the glow plugs should go to the other big terminal. In this case, it doesn't matter which of the two large terminals you use, as long as the wires going to the plugs is on the terminal opposite the wire going to the battery. Regarding the ground and the glow plug controller wires, my memory's a bit fuzzy. IIRC, the relay also grounds to the metal tabs on the bottom. So, you should be able to do a continuity check between the metal mounting tabs and one, then the other small terminal. Connect the ground wire to the small terminal that has continuity with the mounting tab, and connect the controller wire to the other small terminal.

I'm about 85% sure on this...if I'm wrong, someone please correct me!! Unfortunately, I don't have my old GP relay handy to test. You can test the relay function, however. The '83-'86 glow plug system doesn't sense current running to the plugs, so the relay and controller will function the same way with the plugs wired in as with them disconnected. To test it, connect every wire to the GP relay as I described, except for the wires going to the glow plugs themselves. There should be a wire going to the glow plug light in the cab (IIRC, it's dark green); connect this to the large terminal opposite the wire going to the battery (the same terminal that the wires to the plugs themselves will go onto). Then, turn the key ON. If the light cycles normally (on for 8 seconds, off for 10 seconds or so, then back on), it's wired correctly...if the light stays on solidly, reverse the glow plug and ground wires and try again. If the light still stays on solid, the controller may be stuck.

Regarding the other wires, I'm not sure which wires you need info for and which you're okay with. I have a wiring diagram here (a factory shop manual for an '84); if you can give me the colors/striping patterns for the wires you need info on, I should be able to tell you what the wire's for (and therefore where it goes)

There is a wire that runs along the positive cable to/from the starter solenoid. Is that a ground or positive line?

If this is the wire I think you're talking about, it's the trigger wire for the starter. It would go on the large terminal on the fender-mounted starter solenoid opposite of the terminal that you connect to the battery.

Does the little metal cylinder get attached to ground on the fender or not at all?

If you're talking about the condenser that's laying on the battery in the third picture, on my truck, it's grounded. One of the screws that holds the voltage regulator down, also goes through the eye that's wrapped around the condenser.

There is a black wire that looks to have a ground connector on the end, can I run that directly to the battery negative post?

Was this in one of your pictures? ...there are a number of ground eyes in this area, most of which are grounded to the fender. But, I don't see a reason not to hook them directly to the negative terminal, except for issues with lengthening the wire(s) and messiness on the battery.

Also, on the drivers side under the brake master cyl, there are a couple of connections that don't seem to go anywhere, one with a blue connection and the other has two brown lines that come together in a brown female spade connector. Like I said, need a "little" help.

Could these wires be for the water separator? Another possibility is that they're meant to go into a relay that's mounted on the driver's side fender on some trucks, meant to supply power to the running light circuit on the trailer plug in the back. I'm not sure either way, though...

I hope this helps a little bit...good luck!!

 

[dieselutheran2]

Warden, thanx so much for the info, that helps a lot. Question on the factory water separator, how many wires go into that sucker? The factory bit has been replaced with a Racor 220 series. The lower left picture has the two connections on the drivers side, the one with the blue connector looks like a ground; and there are a couple of springs mounted on the fender-well for trailer wiring? is that where the connection goes? How would I use a multi-meter to test the ground continuity of the GP relay to find the ground post? The last picture, lower right, is of two black wires in the loom on the passenger side that join in a male spade connector, the female spade connector has what looks like a ground terminal, can this be hooked directly to the neg battery terminal? Also, since there are two relays, should I run a jumper wire from the battery post on one to the battery post on the other? Thanx again

 

[The Warden]

Question on the factory water separator, how many wires go into that sucker?

A total of 3 wires. They should come together in a single plug, unless someone has fiddled with it in some way.

The lower left picture has the two connections on the drivers side, the one with the blue connector looks like a ground; and there are a couple of springs mounted on the fender-well for trailer wiring? is that where the connection goes?

Oh! ...It was about 0300 when I wrote my earlier post, so I wasn't thinking 100% straight, and I didn't look at the last two pictures in any detail. The two connectors in that picture are NOT for the water separator. I am not sure what they are; I'd need to look under my hood (and I can't now; maybe tomorrow?)...

How would I use a multi-meter to test the ground continuity of the GP relay to find the ground post?

There should be a setting on your multi-meter to test continuity. When you have it set at the right setting, if you touch the leads together (or if you touch the leads to two different pieces of metal that are electrically connected to one another), the meter will beep or buzz or something on those lines. Your meter MAY not have the setting; if it doesn't, you can test for continuity using the ohm setting on the meter; just set it to the most sensitive setting, zero out the leads, and touch one lead to the metal tab and the other lead to each terminal, one at a time. There should be 0 ohms on the ground terminal (the positive terminal MIGHT not show infinite resistance, but it shouldn't be 0, either).

The last picture, lower right, is of two black wires in the loom on the passenger side that join in a male spade connector, the female spade connector has what looks like a ground terminal, can this be hooked directly to the neg battery terminal?

I THINK that that's a ground, but I'd need to look under my hood to be certain. If it's a ground, then yes, you can hook it directly to the negative battery terminal.

Also, since there are two relays, should I run a jumper wire from the battery post on one to the battery post on the other? Thanx again

Yes, you can do that...in fact, if memory serves, that's how the factory wired it. I don't remember if the power feed from the battery went to the glow plug relay with a jumper wire going to the starter relay, or if it's the other way around, but I don't think it matters in this case. FWIW, the other positive power feeds (into the cab fuse box, etc.) are located on the battery feed side of the starter relay...

 

[typ4]

I dont want to sound like a butthead or anything but if you dont know how to use a meter be careful with the wiring. I wouldnt assume anything is a ground or power feed unless something dosnt work on the truck, these trucks have a lit of "extra " things hanging around tow package wiring and the like. Wiring is one of my strong points and I would hate to have you burn your harness.
Is the relay you are using for the glowplugs for them or is it a starter relay??
IIRC they are different but it has been a while since I worked on the older system.

 

[dieselutheran2]

Alright, I hooked up the wires today and have some follow-up questions. I attached the positive lead of the battery to one side of the GP relay, along with a positive lead from that relay post to the starter relay on the fender. I put all the other wires with fusable links on the other side of the GP relay. I attached the ground wire to the post closest to the engine on the GP relay, an the purple GP Controller wire on the other small post closest to the fender. On the starter relay I put the starter trigger wire (black) on the post opposite the one hooked up to the positive lead from the battery/GP relay. I put the red/blue wire on the top post of the starter relay (next to S, not I).

Now to the question. I tested the yellow wires on the wiring connection for the ignition switch on the steering column, nada. No juice. One of the wiring diagrams I have states that the big yellow wires are constant power. Shouldn't they register 12+ volts at all times? Next, the wiring diagram I have shows that I should only have a large orange/white and a green wire with a blue fusable link that changes to black/pink. Should the two other wires go to the post opposite the battery line on the starter relay? How can I get constant hot to the yellow ignition wires? thanx

 

[dieselutheran2]

typ4, thanx for the post, i appreciate your concern ($$$). I have some experience using a multi-meter and reading a wiring diagram, HOWEVER, I don't want to burn this wiring harness either and, THEREFORE, I am preceeding with extreme caution into this truck. I am asking questions to verify what I am going to do is right, and to verify that what I have been doing is in fact correct. That is why I am posting A LOT of pictures and words to go with them. Remember, there are no stupid questions

Below are the two relays that I have in the truck and another angle on the wires on the passenger side of the engine compartment.

 

[typ4]

Ok I just dont mind a little stern teaching , it is just to save people grief. I have made costly mistakes and they arent fun. I may be working at SFO in a couple months and maybe we can meet and greet if so??
ps, when wiring burns it smells bad also.

 

[dieselutheran2]

Yeah, I experienced that smell already. The PO had wired in a GMC GP controller, the plugs weren't heating, and I ended up burning a ground wire. I had to buy a "new" wiring harness from towcat (other user) and now I'm baby-stepping my way through this because I don't have another $250 on hand. BTW the middle pic on the previous post is the GP relay that I just picked up at Kragen/Checker.

I need this truck to work by/before April, I'm moving my family 1300 miles in May and I want some time for driving and tuning.

 

[jimraelee]

Now to the question. I tested the yellow wires on the wiring connection for the ignition switch on the steering column, nada. No juice. One of the wiring diagrams I have states that the big yellow wires are constant power. Shouldn't they register 12+ volts at all times? Next, the wiring diagram I have shows that I should only have a large orange/white and a green wire with a blue fusable link that changes to black/pink. Should the two other wires go to the post opposite the battery line on the starter relay? How can I get constant hot to the yellow ignition wires? thanx

I didnt see an answer to your question. Yes you will need a wire from the battery to the ign switch on the column. Color, I don't really know you need to find that out from your diagram. But basically you need a power wire to the ign switch, so the ign switch will send power back out to the relay on the fender, to connect the always hot lead from one side of that relay to the other side and down to the starter. Logic would tell me that when you hit the first click (run position) that there is a lead that goes to the GP controller and engage the GP relay so that you get the "WAIT TO START" light and can start the truck.
If your up working on this I should be up for a while... working all night.

 

[dieselutheran2]

this is the wiring diagram I am working from. Welcome to it.

 

[jimraelee]

Stupid me... we need to consider is this an automatic??? they have neutral safety switch inline between the ign and the starter relay
Your RED LT GRN is comming out of the ign switch to the GP system
and RED LT BLU is going to the neutral safety switch then to starter relay, so trace them wires and let us know

those diagrams came thru real nice...

 

[dieselutheran2]

Where might I look for the wiring for the neutral safety switch on the truck? what kind of connector does it have? The above diagram shows red/lt blue and white/pink wires. red/lt blue goes to the ignition switch, white/pink goes to the eec module pin #30. now, what does that mean?

 

[towcat]

Where might I look for the wiring for the neutral safety switch on the truck? what kind of connector does it have? The above diagram shows red/lt blue and white/pink wires. red/lt blue goes to the ignition switch, white/pink goes to the eec module pin #30. now, what does that mean?

jesse-
the neut safety switch is down on the trans. It's part of the chassis harness.
I don't have an intact 83-86 truck here at the moment, but I can check on Brian's truck later on this morning for the color. Also, the switch doubles up for the backup lights too. You really shouldn't have much guesswork since the body harness is plug-n-play to your "newused" body harness.

 

[dieselutheran2]

"shouldn't have much guesswork" was my thought too. I'm really stumped why i don't have any power at my ignition switch. Which wires (color and fuse link size/color) should be hooked up to the relay post with the positive lead from the battery, if any?

nice avitar by the way!