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Thread: 1998 Driveability problem and code P1518

  1. #1
    Join Date
    May 2019

    Default 1998 Driveability problem and code P1518

    Hi,I'm having a problem with my 1998 auto. conv. It has an intermittent running problem where it has no power, can't accelerate,a Reduced Power message comes on and it is setting codes P1518 Tac Module and P1571 Traction Control. Cleared the codes and it ran well again for a short time but then it went back to running bad and re-setting codes.Did some research and found that 97 and 98 cars had problems with the TAC module.Tried to buy a new one but they were unavailable so I settled for a supposed good used one.I had assumed that I was going to be removing the original module but the part number looked to be a replacement of the original one like someone has already changed out the problem one with the bad part number. In any event it still has the same problem with a different module.I've also cleaned every ground that I can find and doing wiggle tests on wiring harnesses under the hood and at the gas pedal,tapped on the throttle body motor and the gas pedal sensor. Not sure where to go from here. Any suggestions would be greatly appreciated. Thank you,Jack.

  2. #2


    Good morning,

    I would suggest a few things here.

    #1, check your terminal tension at the TAC module, as I have seen a few issues there.

    #2, make certain the harness loop around the PCM and the TAC module has not chaffed a wire through the plastic conduit.

    #3, make certain you have the latest programming updates for the engine control module/ECM. There was an updated calibration to address the P1518.

    Allthebest, and keep us posted, Paul
    GM World Class Certified Service Technician.
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