Buick Engine Idling Very High After Jump Start

IAC motor. Idle control valve controls idle speed.

I have a 1995 Buick Century special (sedan). the newer v6, 3.1. I just replaced the whole wiring engine harness due to a small electrical fire from some stupid people that tried to jump another car in the dark and the red positive jumper wire touched the air cleaner cover and started a fire and did not bother to disconnect the negative jumper wire and burned in 2 places. the whole battery wires, both red and black and around that area and other the other side near the relay switches. Now, making a small story, i replaced the engine wiring harness, car started, runs, everything works.

One problem, when i start the car and have it running for a few seconds, the engine idle speed start idling very high and the SERVICE ENGINE SOON light comes on. There is no vacuum leaks. Can it be the IDLE AIR CONTROL VALVE? How can I test it to see if its bad or good?

Also, I have also a obd1, 2 scanner and I cannot get the codes and I cannot even use a paperclip because there no A or B Terminals, only 3 wires comes out of the obd1 (Data link connector) the wires are purple, orange and black with a white strip on the left side, why is it they call it a 23 pin and its only 3 wire coming out of it? I need help really bad, I want my Buick to run good as it once were.

With an entire engine harness replaced because of the jump start and fire, this is going to be very hard to help you with. There could be damaged wires that you did not see yet. If when the wires melted, some of them that had power must have very well shorted to ground or to each other. That could have damaged any computer module in the car, especially the PCM .

Did the replacement include the fuse box and relay center under the hood? These could have melted internally or at least melted wires under the box.

This Buick Century is early OBDII, so you will not be able to use the old paperclip method to pull the codes. If you are sure your scanner works for this system and you still cant read codes, Then use might have a bad PCM or the data wires are damaged. If you cannot power the scanner up, then it is a power or ground problem to the diagnostic connector. If it does power up but no communication, then as stated, the PCM could have gotten damaged.IAC motor. Idle control valve controls idle speed.

To the the idle air control valve, you need to use a scanner to control the output to it and use a volt meter to test for proper voltage at the connector. Or remove it to see if it moves. There is also a special IAC driver tool that you plug in and control it to see if it moves.

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