Speedo inop

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12-10-2003, 06:53 PM
L-Eater

Somebody tell me what I did wrong. 1994 full size P/U with 2002 5.3/4l60e. I ran the VSS wires coming out of the PCM to the DRAC module under the dash to the terminals where the original VSS was hooked. I got no speedo at all. Am I overlooking something obvious? I won't have time to trace wires and check the service manual for a couplr days. :whack:
12-10-2003, 10:34 PM
farmtruc

Mine is also a '94, i'll check mine tomorrow and my books and see whats up.
12-11-2003, 08:28 AM
L-Eater

OK, thanks. I think I already know what is up. I used the wires coming out of the PCM (which have a "processed signal") to hook to the DRAC. The DRAC is a "processor" which when the truck was stock took the signal from the VSS and processed it for the cruise, speedo, abs etc. I think I need to hook the DRAC to the actual VSS wires coming from the tranny, not the VSS wires coming out of the PCM. Does that sound logical?
12-11-2003, 08:45 AM
GMCwantsLS1

I think I would bypass the DRAC and hook the speedo directly up to the PCM. That way you can calabrate the speedo with the PCM for gear and tire changes.
12-14-2003, 06:53 AM
L-Eater

I ran the actual VSS wires to the DRAC anda it still didn't work! Then I remembered that I never plugged the DRAC back in after unhooking it to test some wires. Now it works fine. DOHH!!
12-14-2003, 07:32 PM
GMCwantsLS1

Cool so what was the final wiring? I think Farmtruc still needs to get his hooked up! :thumb:
12-14-2003, 10:54 PM
farmtruc

Quote:

Originally posted by L-Eater@Dec 14 2003, 05:53 AM
I ran the actual VSS wires to the DRAC anda it still didn't work! Then I remembered that I never plugged the DRAC back in after unhooking it to test some wires. Now it works fine. DOHH!!

ya, how did you hook it up and can you give specifics.

thanks,

allen
12-15-2003, 07:18 PM
L-Eater

OK, I took the factory Lt Green/Black wire and the Purple/White wire that runs from the DRAC to the VSS on the tranny in stock configuration on the 94 truck and cut it in the engine compartment. These wires are a twisted pair enclosed in black insulation. Take the ends and run them to the new PCM and hook them to terminal 20 and 21, respectively. The wires are color coded at the PCM. Hook into them but leave them intact (just "skin back the insulation without cutting the wire) and twist and solder the wires from the DRAC and you are done!