QuestionQUESTION: 96 deville with northstar.....Well I did everyting u told me about getting rid of the p1660 code. Changed all 3 relays,pcm did the ground test on relay 2 or 3,unplugged the engine coolant temp sensor while car is in on not run position. The fans did not come on when i unplugged it so i changed the ect,reset computer and code came back within 5 minutes. Even when i put the new sensor in i unplugged it after resetting the fans still dot come on. Is there something else. Bad wiring maybe. When I did the ground test with a toggle switch the fans did come on to max speed but u said not to leave on cuzz it could hurt the pcm and/or ac.
ANSWER: OK, It appears that you have verified that you have battery voltage going to the 3 relays and the ground circuit is OK.
Therefore the QUAD DRIVER in the PCM is faulty. Replace the PCM and CLEAR the code from the computer.
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QUESTION: Follow up question from last week about my 96 deville northstar p1660 code. You told me again to replace my pcm to fix this code. I remember telling u i did already along with all 3 relays,ect sensor,did ground test,ect. Im stuck is there something else. Maybe recharge my ac so my compressor can come on...i looked in some schematics and i think relay #2 is linked to the ac compressor relay. could that be the problem?
AnswerIt is linked but all it does is rngage the compressor.
We are missing something simple here. I wish you were close to me so I can run the tests.
Did you check ALL the applicable fuses ?.
Do you have battery voltage at ALL times to the RED wires on relay 1 and 3 ?
Do you have battery voltage at the AC COMP fuse in the engine compartment fuse box at ALL times ?
Do you have battery voltage at the ECS fuse with the ignition ON ?.
If you jumper the dark green wire from cooling fan relay #1 to ground do the cooling fans run on low speed ?
If you jumper the dark blue wire from cooling fan relay #3 to ground do the cooling fans run on high speed ?
