Getting a Malfunction Code on your 1986 1987 Buick Grand National, T-type, Turbo T, etc.?
If you don’t have a scantool or similar device that reads the codes for you, here’s the way to do it old school!
How to check for malfunction codes manually:
1. Find the ALDL connector that is under the dash, below/behind the radio.
2. With the ignition ON and the engine OFF, jump the terminals “A” and “B” using a paperclip or similar.
(A&B are located next to each other; both are located on the top row. “A” = the very top right hole; “B” = 2nd hole to the left of the top right hole).
[“A” is a ground, “B” is the Diagnostic Terminal].
3. watch the check engine light, count the number of blinks it makes.
(there will be a pause between the first number and the second number).
4. The Code 12 will flash three times first (indicating the system is operating correctly) followed by any other trouble codes that are stored in the memory (if any).
5. write them down as you go, there may be more than one!
To clear your error codes, disconnect the orange wire by the battery briefly and this will reset all the codes.
(this wire is connected to ECM).
Here’s the listing of the error codes your turbo regal may display:
Error Code # – Description of error code:
12 – Error Code System Functioning Correctly
13 – Oxygen Sensor (O2) Circuit OPEN
14 – Coolant Temp Sensor Circuit (High Temperature)
15 – Coolant Temp Sensor Circuit (Low Temperature)
21 – TPS Sensor Circuit (High)
22 – TPS Sensor Circuit (Low)
23 – Manifold Air Temp Circuit (Low Temperature)
24 – Vehicle Speed Sensor (VSS) Circuit Failed
25 – Manifold Air Temp Circuit (High Temperature)
31 – Wastegate Solenoid Electrical Signal Fail
32 – Exhaust Gas Recirculation (EGR) Circuit
33 – MASS Air Flow (MAF) Circuit (High)
34 – MASS Air Flow (MAF) Circuit (Low)
41 – CAM Sensor Circuit Failure
42 – C31 Electronic Spark Timing (EST) Fail
43 – Electronic Spark Control (ESC) Failure
44 – Oxygen Sensor (O2) Circuit (LEAN Exhaust)
45 – Oxygen Sensor (O2) Circuit (RICH Exhaust)
51 – EPROM Error – Reseat or Replace the Chip
52 – CALPAK Error
55 – ECM Error