Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSPONTIAC1986FIREBIRD BASE, 2.5 2REPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSIS5.0L FEEDBACK CARBURETOR "A" CHARTSCHART A6 - WON'T FLASH CODE 12
1986 Pontiac Firebird Base, 2.5 2
Chart A6 - Won't Flash Code 12
1986 Pontiac Firebird Base, 2.5 2SECTION Chart A6 - Won't Flash Code 12
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This step checks for short to battery voltage in wire to terminal "C" or faulty light driver. Normal reading is 9 to 11 volts.
- This step checks to see if problem is related to the ECM or light driver. Grounding terminal "C" should turn light off.
- Grounding terminal "G" at ECM and finding light on indicates an open in wire to terminal "C" of light driver. Grounding terminal "G" should turn light off.
- This step checks for open in wire from ECM to test terminal in ALCL connector. The light should flash Code 12 when terminal "5" is grounded.
- This checks for proper voltage supply to ECM. Both should read over 9 volts. Term. "C" is ignition and terminal "R" is constant battery voltage for long term memory.
- This test checks for bad ground in ECM. Terminals "A" and "U" are connected together inside ECM.
- This step distinguishes between a faulty ECM and PROM. Normal response is for Code 51 to flash even though PROM is not installed in ECM. If no Code 51, ECM is faulty.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.