1995 Pontiac Grand Prix ALDL connection - wiring

  • 6 CYL
  • FWD
  • 53,000 MILES
I have a Haynes repair manual and was trying to diagnois a problem with a hesitation condition at around 2100 rpm and from 45 mph and higher when giving pressing the pedal down slightly. In the manual it says that a 12-pin connector is a ALDL and a 16-pin is the OBD-II and my vehicle is the 12-pin.

Manual says to jump the "A" (ground) and "B" (Diagnostic terminal) terminals which the diagram shows them to be the 1st and 2nd from the right top connectors, which should flash the codes via the "Check Engine" light but nothing happend.

I removed the connector to check the wiring and "B" terminal has no wire and there were only three. There is one "Black" wire, one "White" wire and one "Green" wire only to this connector.

My question is can I install a jumper wire between two of these colored wires to receive the flash codes on the dashboard?
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have the same problem?
Wednesday, September 9th, 2009 AT 10:27 PM

1 Reply

DIAGNOSTIC CIRCUIT CHECK The Diagnostic Circuit Check determines: If Malfunction Indicator Light (MIL) works. If PCM is operating and can recognize a fault. If any codes are stored. After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. See Fig. 8 and Fig. 9 . After performing necessary tests as described in the diagnostic circuit check, if no codes are indicated and driveability problems still exist, see H - TROUBLE SHOOTING - NO CODES article in the ENGINE PERFORMANCE section and SCAN TESTER USAGE in TESTS W/CODES article in the ENGINE PERFORMANCE section. 1. Check operation of MIL. Turn ignition on with engine off. MIL should be on steady. If MIL illuminates and stays on steady, go to step 3). If MIL does not illuminate, go to A-1, MIL INOPERATIVE. If MIL flashes, go to step 4). 2. On vehicles equipped with 16-pin DLC or 12-pin DLC without test terminal "B", install Tech 1 scan tester and follow scan tester manufacturer's instructions to proceed with test. If MIL does not come on, go to A-1, MIL INOPERATIVE. If MIL comes on, check for diagnostic trouble codes and diagnose codes using TESTS W/CODES article in the ENGINE PERFORMANCE section. On vehicles equipped with 12-pin DLC with test terminal "B", go to next step. 3. Grounding DLC terminal "B" at this time should cause MIL to flash a Code 12, followed by any codes stored in PCM memory. See Fig. 5 . MIL going from bright to dim is not considered a code. If MIL dims or remains on and does not flash Code 12, see A-2, MIL ON STEADY OR WON'T FLASH CODE 12. 4. If MIL begins to flash as soon as ignition is turned on, check for a short to ground on the diagnostic test terminal wire between DLC terminal "B" and PCM terminal No. 5. If circuit is okay, replace PCM. NOTE: On vehicles equipped with 16-pin DLC or 12-pin DLC without test terminal "B", use of Tech 1 scan tester is required to perform diagnostic circuit check. See DATA LINK CONNECTOR (DLC) TEST TERMINALS table. NOTE: On some models, as long as a 30-second pause may occur between code flashes. This is normal and does not indicate necessary component replacement.
9/10/2009 ...


Does the ses light come on with the key turned to ON?
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Thursday, September 10th, 2009 AT 3:52 PM

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