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Loose Connections (Wiring & Vacuum) 5 parts w/ pics

FightinTXag

FightinTXag

1/2 ton status
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Apr 11, 2006
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Location
Fort Worth, TX
Background
Ok, so the PO of my truck (85 K10) wrecked it pretty good. Since there was considerable damage in the door jamb, he decided to swap another cab (including wiring) onto it. The cab apparently came from a truck that had a handful of different options - for instance, it has a dual tank switch on the dash even though there are not 2 tanks and the IP wiring harness has no wire to the pin connection for the 4wd light so the truck was probably 2wd.

Question #1
The turn stalk has cruise, but it has never worked. I found it has no cruise servo, so I bought one off ebay. I'm guessing the truck originally didn't have cruise, but the cab is outfitted for it. In the picture below I've got the wiring connection and the large vacuum hose in yellow circles that appear to be for the cruise servo. They're harnessed together and come through the firewall from the cab. I plan to mount the servo, connect the wires and vacuum hose from this harness and provide manifold vacuum from the capped connection circled in red. Assuming everything in the cab is hooked up correctly (brain box, brake switch, and wiring) should this make my cruise work? Is there anything else outside the firewall I should check given that the truck may not have originally had cruise but the cab seems to be set up for it?
100_0657.jpg


Question #2
I've got a black plastic connection with one pink and one white wire coming from the junction block thingy on the driver's side of the firewall. No idea where these go. Could it be something for the dual tanks?
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Question #3
I've got a black rubber connection with one dark green and one light green wire coming through the firewall near the driver's side valve cover. In fact, in the image below it's sitting on the valve cover. Any idea what this is for?
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Question #4
I've got a ring terminal that looks like it should be for a ground coming through the firewall near the passenger side valve cover. I'm holding it in my hand in the picture below. Is this a ground? Where should it go? Cab? Engine? Frame? Does it matter?
100_0663.jpg


Question #5
I've got what appears to be a ground strap hanging from the passenger side cylinder head. Should this go to the frame or cab? Not sure it'll reach the frame. You can see it's pretty close to the ring terminal I asked about above (that's it in the foreground). Should they be grounded together somewhere?
100_0664.jpg


Thanks for your help
 
most electrical grounds threw motor block then to frame rail then to batt. so in pic #4 go to block and #5 go to frame as it looks like its on the block now.
 
#5 is the head to body ground. I see a rust spot in #4 that may be where it goes, it was just a large sheetmetal screw holding them in place.

Two green wires look like the manual trans backup light wiring.

Do an advanced search, for my username and thread title "wiring" and you'll find my post that has links to truck wiring manuals.
 
Two green wires look like the manual trans backup light wiring.
Click to expand...
Hmm, that's interesting. I had searched for "dark green" and "light green" wires and all I found was backup light and speaker stuff. My backup lights work so I figured that couldn't be it, but I hadn't thought there may be provisions for backup lights from a manual tranny hanging out of the cab.

I guess it's possible. The tranny hump has been cut out and a patch panel from (I guess) the wrecked cab was put in it's place to get the cutout for the transfer case shifter.

Are there any telltale signs I could look for to find out if that cab was originally for a manual tranny? There are no obvious indications (clutch pedal or smaller brake pedal). The donor vehicle's vin is still on the cowl. Can the transmission be deciphered from the vin?

Do an advanced search, for my username and thread title "wiring" and you'll find my post that has links to truck wiring manuals.
Click to expand...

I've got an '85 factory service manual (got in on ebay for $10 - cheaper than the Chilton Manual I got from Oreilly) with all the wiring diagrams, but it's tough to find out what some wires are for when you don't even know what system/circuit they're for.
 
I don't know as GM can go back and tell you what tranny was in the truck when you got it, that far back.

Now that I think about it, the reverse wiring might be a flat connector up in the engine bay, but as I recall, the actual tranny end on the early 465's (up to about '84 I'd suspect) reverse light connector is that round style, with the two slots perpendicular to each other.

With only two wires, off the top of my head thats all I can think of that used that sort of plug. There were enough things used on these trucks though (trans spark control, etc) and enough changes year to year, that I'm not intimately familiar with to be certain.

Even your '85 manual can be "wrong" because the wire colors may have changed. Only way to be 100% (or close) is to know exactly what year you are dealing with and have the appropriate diagrams. You may want to find my link and check out the '83 stuff though, maybe the color change was a year difference. I don't believe anything in '85 still used those connectors though, it was all weatherpack...taillights, rear window, reverse light on tranny, etc.
 
The green wires wouldn't related to TCC lockup would they?

There are dark green and light green wires together in a flat connector pretty close to this plug. Take a look towards the center of Pic #1 above the distributor. The dark green in that wire runs to the a/c compressor and the light green goes to the a/c idle kickup thingy on the carb.
 
TCC I believe is three wires. Not aware that it had another disconnect between the source and the tranny.

Pick one or 4 shows the TCC Vacuum switch, (for reference) I just can't recall which side it is.
 
I'll peruse the wiring diagrams in my manual again when I get home. If that doesn't help me figure out what these are for and nobody chimes in with a definitive answer, then I may take a stroll through the junkyards tomorrow to see if any of 'em still have these wires hooked up.

I found it interesting that those other dark green/light green wires for the a/c idle kickup are so close. But I can't figure out how or why these guys would hook into that circuit.
 
Looked through the junkyard today and the dark green/light green connector appears to be for the dual tank setup. None of the K5's, Burbs, or pickups without dual tanks have this wiring or connector. Traced them on a dual tank pickup that had both tanks removed and they went to a 4 or 5 wire flat connector on some kind of electronic device near the passenger side tank.

The pink and white wires appear to go to the top connection on the wiper motor for most trucks. But I don't have any place for the connector on my wiper motor. My wipers don't work on high either. The white and blue/black wires going up in pic #2 are the only ones going to this area of my wiper motor. Anybody got any suggestions? I'll be checking the wiper system out in my wiring diagrams.
 
Boy no wonder that dual tank wiring is so much of a pain to figure out! (do a search for fuel wiring lol)

There are two wiper setups used, later was the two separate plugs, I just can't recall what the differences are. One difference is the pump mounted washer motor vs. tank mounted, but IIRC, the wiring itself was changed for the motors. I know I had to add wiper wiring to the firewall connector to match up with the later fuse panel.
 
I don't know what's going on with those pink and white wires. At the junkyard some had these wires connected to the motor others didn't have them at all. Then I came home and read that in '85 they switched from a washer pump integrated with the motor to a separate pump in the resevoir. I have pink and white wires going to the resevoir in addition to these hanging loose.

So I began to think that it seems as though my truck has provisions in the wiring harness for either style of washer pump. It looks like they could hook up either the resevoir mounted one that I have and leave this connector loose. Or if a motor mounted pump was used, then this connector would be used and the one I've got going to my resevoir would be loose.

But then I got to looking more closely at my GM service manual's wiring diagrams. In the standard diagrams it shows that no pink or white wires should be coming from this junction on the firewall. Futhermore it shows no circuits in the slots these wires occupy in the firewall junction. But, if you look at the supplemental diagram showing the wiring for the V22 option (which is deluxe front appearance with quad headlights), suddenly circuits 94 and 91 occupy those slots and pink and white wires should be coming from them and connecting to the wiper motor. :confused:

I have quad headlights (see my avatar) so maybe someone replaced the wiper motor with the wrong one and I should have one that has a place for these wires. But LMC doesn't show there to be more than one wiper motor for 85-87 trucks. Furthermore WTH would quad headlights have to do with wiper wiring?:dunno:

My head is spinning now. And I'm not even sure if this would be related to my problem of the wipers not working on high or not. My wipers are the same slow speed on high as they are on low. Could be the switch instead of the motor.

Unless someone can straighten me out on this deal, I'm gonna go back to the junkyard and buy a motor with the spot for this connection and see what happens.
 
That motor is exactly like mine and hooked up in the same way. If you look at TPIjune2, between the mc resevoir and the washer resevoir, you can see the pink and white wires go into a loom and then into the resevoir. Mine has the same wires going to the resevoir.

But then mine has those other pink and white wires hanging loose. My wiring diagrams seem to indicate if you have quad headlight their should be a 3rd connection on the motor. Which really doesn't make much sense. Does the truck in that TPI swap have quad headlights?
 
Went to the junkyard today to investigate some more. This time I paid more attention to the model year code in the vins. I found one other '85 pickup and one '84 suburban that had those extra pink/white wires hanging with no place for them to go just like mine. Both were also a dual headlight setups (so that apparently isn't a factor), with resevoir mounted pumps.

Maybe the washer pump change didn't exactly coincide with the model year change? I'm guessing late in '84 you could end up with either washer setup. Consequently late in '84 through early in '85 the wiring harnesses would accomodate either washer setup. By late '85 they had eliminated the extra connector as I saw a couple '85s and all of the '86+ trucks without it.

Of course that's all speculation on my part, but the bottom line is that I don't believe those wires need to be connected to anything.

I also ran the ground test and got my wipers cycling at high speed so apparently the switch is the culprit. I understand those column mounted switches are a ton of fun to switch out.

So I think all 5 of my questions have been answered. Thanks.
 
Yep, my truck has quad headlights.

BUT, the wiper wiring shown was added to the firewall connector, as the engine side of the harness was setup for the "old" motor. Fuse panel was new enough so that I didn't have to mess around with that side.

And hopefully you DO have the wires sorted out. Aren't the year changes/options fun? :)
 
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