Hello everyone I’ve recently purchased this car for a great price, the last owner I believe tried to repair it himself and gave up.

I’ve found a post on here very very similar to mine found here I’ve tried all the stuff on there including a new PCM AND tried what Ben answered.

I have alldata and have wiring diagrams so I’ve been tracing circuits left and right.

I’ve found that pin D12(pink and black wire) on connector x2 on fuse box is only getting 7.6 volts. I also traced that wire to pin 1 on the PCM.

I know that relay 33 POW/TRN circuit powers that and the injectors as well as ignition coils are powered from that circuit. I also am getting 7.6 volts at the relay.

What feeds relay 33? I can’t seem to find it

UPDATE: when I checked the resistance between pin D12 and pin 30 of relay 33 terminal I get 4.7k ohms this is definitely a problem right?

UPDATE:I found the PCM issue... it was the ground cable that ground to engine block near then starter. Now the issue is it cranks but no fuel injector pulse, also I am getting code p1682.

  • Welcome to Motor Vehicle Maintenance & Repair! What is the battery voltage? Aug 16, 2021 at 22:11
  • 12.6 volts... okay so I figured it out it was the engine block ground, now it cranks but it still won’t start and now I get p1682
    – BlarginBro
    Aug 17, 2021 at 1:34

1 Answer 1


What wasn't discussed in the other thread and this one is relearning the fuel password when replacing the pcm or bcm. The fuel password is GMs antitheft feature of Passlock security - disabling injectors when the security indicator is flashes. Other GM models disable the starting circuit. Your description of zero injector operation seems to be a Passlock issue. A relearn procedure is described in your alldata service manuals. Either a ten minute GM dealer procedure using their scantool or diy at home thirty minute procedure. This procedure relearns the fuel password, marrying the pcm to the bcm. The bcm has Passlock programming sending the fuel password to the pcm to allow injector operation. Review alldata for the relearn procedure without GMs scantool. P1682 may be the incorrect low voltage and corrected so this error should reset once Passlock is relearned.

  • Thank you for the reply! I don’t have security light on, but I also didn’t see it when you first turn the key, maybe the light is out?
    – BlarginBro
    Aug 17, 2021 at 2:55
  • While not completely familiar with every GM model, my '03 GM has Passlock. Paper service manuals.. Other GM forums share info about Passlock. Please use alldata for info related to factory security. Leds are used and rarely fail for specific indicators.
    – F Dryer
    Aug 17, 2021 at 3:23
  • That’s what I thought I figured the lights rarely fail
    – BlarginBro
    Aug 17, 2021 at 3:29

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