CEL Light Problem
#1
11-02-2006, 08:46 PM
CEL Light Problem
Question for the experts.
On my 1995 MC 3.4 Litre with OBD1 (I'm told), when I jumper "A" to "B" on the ALDL, the CEL stays on continuously.
Does this mean pin "B" is shorted to the ground of the CEL?
TIA,
jogasz28
On my 1995 MC 3.4 Litre with OBD1 (I'm told), when I jumper "A" to "B" on the ALDL, the CEL stays on continuously.
Does this mean pin "B" is shorted to the ground of the CEL?
TIA,
jogasz28
#2
11-03-2006, 07:47 AM
RE: CEL Light Problem
More info (hopefully it'll help):
When I measured between ALDL pins "A" and "M", the voltage stayed between 1.21 VDC to 1.29 VDC with the engine cold or warmed up (using a Fluke digital VOM). The Factory Manual says the voltage should vary between 3-5 VDC as it is the data line to ground circuit.
Also, the "SECURITY" Instrument Panel light stays on all the time.
Any ideas?
Jogasz28
When I measured between ALDL pins "A" and "M", the voltage stayed between 1.21 VDC to 1.29 VDC with the engine cold or warmed up (using a Fluke digital VOM). The Factory Manual says the voltage should vary between 3-5 VDC as it is the data line to ground circuit.
Also, the "SECURITY" Instrument Panel light stays on all the time.
Any ideas?
Jogasz28
#3
11-03-2006, 03:07 PM
RE: CEL Light Problem
well one problem! your not OBD 1. and sadly your not OBD 2 GM jumped the gun in 95 and released an early version of obd2 this version has come to be called obd 1.5 as far as i know you cant jumper obd 1.5 the securty light normally only comes on if there is a prob with the ignition system... you know that little plug in your key. that is the VATS system.
take the car to autozone i have heard one person getting it scaned there. if not pay the $ and get GM to scan it.
take the car to autozone i have heard one person getting it scaned there. if not pay the $ and get GM to scan it.
#4
11-03-2006, 06:37 PM
RE: CEL Light Problem
Here is an OBD 1.5 defintion:
OBD 1.5 is an OBD I system with the 16 pin OBD II diagnostic connector. An OBD I code reader must be used. It is only believed to be used by GM in 1994 and 1995. OBD1.5 has also been used on Mitsubishi cars of '95 '97 vintage.
My ALDL connector is a 12 pin, and not Mitsubishi.
Are you sure of your info?
jogasz28
OBD 1.5 is an OBD I system with the 16 pin OBD II diagnostic connector. An OBD I code reader must be used. It is only believed to be used by GM in 1994 and 1995. OBD1.5 has also been used on Mitsubishi cars of '95 '97 vintage.
My ALDL connector is a 12 pin, and not Mitsubishi.
Are you sure of your info?
jogasz28
#5
11-04-2006, 01:28 PM
RE: CEL Light Problem
Found something important about my '95 MC
Checking the factory manual and actual ALDL pin out wiring, I have found that there are only 2 pins on the ALDL, the "A" and "M" pins. "A" is PCM ground (at the steering coloumn), and "M" is the PCM Serial Data. There is no "B" pin. So when I would jumper "A" to "B", with no pin, the PCM just thinks the car is in the on position with no engine running, and turns on the CEL! That's why the CEL stays on!
Anyways, I'm gonna connect my laptop again in the hopes I can get it talking with the PCM.
jogasz28
Checking the factory manual and actual ALDL pin out wiring, I have found that there are only 2 pins on the ALDL, the "A" and "M" pins. "A" is PCM ground (at the steering coloumn), and "M" is the PCM Serial Data. There is no "B" pin. So when I would jumper "A" to "B", with no pin, the PCM just thinks the car is in the on position with no engine running, and turns on the CEL! That's why the CEL stays on!
Anyways, I'm gonna connect my laptop again in the hopes I can get it talking with the PCM.
jogasz28
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