What I did was match the colors with the pin-out on the large A-pillar plug. I then labeled all the wires one by one as I cut them. I will try to re-trace them, but I didn't undo the entire harness the second time around. I left the foam insulation on the wires (kept them a lot neater).It needs switched power (or ignition), ground, and reverse signal (if I can find a convenient location to get that; or else I'll skip it).My dash is out so behind the radio is SUPER easy.I'm re-searching all the threads I looked over a long time ago to double check myself.Finally started working on this today!
I used 2 wiring harnesses. Both were fully un-taped. One was used as the "good" one and the other was cutup and used to lengthen the other harness. I did this to keep everything in the factory color-coding scheme.
Little problem.....it's not working right!![]()
Here's my wiring (from the DIC plug to the pins on the A-pillar plug to the radio):
7 (DK GRN) = P (DK GRN) = Radio PIN 9
8 (BLK/WHT) = F (BLK/WHT) = Radio PIN 5
9 (DK GRN/WHT) = N (DK GRN/WHT) = Radio PIN 16
10 (LT GRN/BLK) = G (LT GRN/BLK) = outside air temp sensor
11 (GRY) = E (GRY) = Radio PIN 7
12 (PPL/WHT) = M (PPL/WHT) = Radio PIN 6
13 = not used in the DIC connector
14 (ORN) = R (ORN) = still connected to A-pillar
15 (YEL) = C (YEL) = to purple ALDL wire
What's happening:
When I put power to the truck, the DIC displays everything with the key OFF (no data is calculated, but the display lights up and can scroll through everything). It displays nothing with the key ON/RUN.
I have absolutely no idea what's wrong. I followed all the info I found online and all the colors match up behind the radio.
Any ideas?Is there a discrepancy between my truck (a '98) and the colors that I'm going by?
Mine did the same thing, with the key off, it can't read the computer.
Double check your wires, and then check them again, make sure your splices are good...
Also, make sure you spin the wires your tapping into, sometimes there's a line that's a PITA to see, making it the wrong wire.
Post up what functions those radio pins are for, please... I don't remember splicing anything to my radio![]()
I triple checked all my wiring before I left the truck this evening.
Here's the wiring for the DIC plug to the radio...or at least I think this is right.
7 = dark green - RAP Fused Supply (tap into DRK GRN, radio PIN 9)
8 = black/white - Ground (radio PIN 5)
9 = drk grn/wht - VSS (tap into dark green, bottom plug of radio PIN 16)
10= lt grn/blk - Outside air temp (this should be the only wire out of the cab to the sensor)
11= gray - Instrument panel lamp fuse supply (radio PIN 7)
12= ppl/white - LED dimming signal (radio PIN 6)
13 = NOT USED
14= Orange - constant 12v (tap into orange wire, top plug of radio PIN 10)
15 = Yellow - Class 2 serial data (ppl wire at ALDL)
Ahh, yes, I tapped into the RAP at the radio, but that's the only wire... I used the instrument cluster for the VSS and the headlight switch for the lights
IMO, tapping into the radio harness for everything is a PITA
I also only ran "one" wire... I used some CAT5E.![]()
I thought about CAT5E, but I wanted to keep everything factory color-coded. Plus, you'll never know unless you remove everything.
I'm just really confused right now....and I still need to figure out where to run the wires for the auto-dimming mirror to.
The mirror SHOULD just need ignition power....
Can I get the ignition power behind the radio? Or any where easy to get to right now?
Honestly, I don't see what's wrong with my current wiring. All the colors and descriptions match up. It's acting the exact opposite as it should. I hate confusion!
Just run the wires to another area... If the dash is out anyway, it's not too difficult...
Instead of matching up colours to colours, trace from the OHC each wire, by function...
Where else can I get a switched power source? It would really be cool if the OHC would come on when the key was turned backwards and to the RUN position (just like the radio does; then I could get a temp reading without turning on the fuel pump).
Try using a different wire in the factory radio harness if that one is giving you issues... When I installed my stereo in my Blazer, there was like 5 choices for switched power

A voltmeter or test light is a great wiring tool
Is there a discrepancy between my truck (a '98) and the colors that I'm going by?
So then I unplugged the door plunger and it still worked. I looked at the headlight control knob plug and there are 2 orange and 1 white wire going to it. I unplugged the headlight control knob and it didn't work right.