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 MANUALSPONTIAC1990FIREBIRD TRANS AM, 5.0 F, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTANTI-THEFT SYSTEMSANTI-THEFT SYSTEMSYSTEM TESTINGPASS KEY DECODER MODULE TEST 1
1990 Pontiac Firebird Trans Am, 5.0 F, Standard
Pass Key Decoder Module Test 1
1990 Pontiac Firebird Trans Am, 5.0 F, StandardSECTION Pass Key Decoder Module Test 1
NOTE:
The following table is used to verify voltage at the Pass Key Decoder Module connector with the connector disconnected and the ignition switch in the "RUN" position.
PASS KEY DECODER MODULE TEST (TABLE 1A)
| Measure Between | Correct Voltage | For Diagnosis |
|---|---|---|
| A1 (PNK/BLK) & GROUND | BATTERY | See 1 |
| B8 (ORN) & GROUND | BATTERY | See 2 |
| A1 (PNK/BLK) & B1 (BLK/WHT) | BATTERY | See 3 |
| A2 (DK BLU) & B1 (BLK/WHT) | 5 Volts | See 4 |
NOTE:
The following table continues to verify voltage at the Pass Key Decoder Module connector with the connector disconnected and the ignition switch in the "START" position.
PASS KEY DECODER MODULE TEST (TABLE 1B)
| Measure Between | Correct Voltage | For Diagnosis |
|---|---|---|
| A3 (DK GRN) & GROUND | BATTERY | See Step 5). |
| * If voltages are correct, go to PASS KEY DECODER MODULE TEST 2 . | ||
- Check the PNK/BLK (439) wire and ENG CNL Fuse for an open.
- Check the ORN (440) wire and VATS Fuse for an open.
- Check the BLK/WHT (450) wire for an open.
- Check the DK BLU (229) wire for an open. If wire is good, replace ECM.
- Check DK GRN (965) wire for an open. If wire is good, do PASS KEY DECODER MODULE TEST .
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.