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I have a 2207 Hyundai Veracruz AWD with 189K miles. Recently the ESC off, ABS and AWD lights all came on. They go out occasionally, but typically come back on within a short period of time. I replaced the brake switch with one from AutoZone.

I brought it into the dealer and the tech wrote the following.

found related dtcs for loss of com with abs set in history. Traced abs concern and found unable to communicate with abs module. Traced to loss of module ign power signal at ecu. Verified fuse. Found condition due to intermittent connection internal in wiring harness. Direct powdered the module and verified com present and found P1753 still sets and no sensor operation or right rear sensor. Fault internal in harness, harness no longer available. Would need to tear down main harness locate fault and repair. Rear sensor fault may also be related to wiring or may be faulty sensor.

So my question is, when he says “Traced to loss of module ign power signal at ecu”, does he mean the abs module? I’m not sure if he’s using the term ecu to refer to the abs module or if he means the engine control unit. I believe the engine control unit is on the passenger side engine compartment next to the relay block an it’s still covered in dust. So I doubt he did any work in that module.

I’m hoping I can just run a new fused ignition wire to whichever module he’s talking about

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  • Not an expert on Hyundais but may suggest a problem indirectly related to ESC/abs/awd intermittent indicators along with possible false error codes; main battery, battery cables, their connections, alternator and drive belt. There's a GM model triggering abs error codes that were traced to battery, battery cables and/or corroded battery connections (negative and two main grounds) and alternator issues. While cookie cutter dealer mechanics are everywhere, experts with advanced knowledge and experience are few and far between. Perhaps examining main power before chasing intermittent gremlins?
    – F Dryer
    Jan 1, 2023 at 18:53
  • Ecu/ecm/pcm all mean the same; engine control computer. If I'm not mistaken, ESC means electronic stability control? ESC/abs/awd are all electronically controlled, requiring a steady power source, hence possible main power issues.
    – F Dryer
    Jan 1, 2023 at 18:56

1 Answer 1

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The tech is stating there are three issues:

  • There's no communications between the ECU and the ABS module.
  • The ABS module is not powering up because it's not getting a signal from the ECU to do so. (The ABS module and ECU are two separate things.)
  • The right rear wheel sensor is showing a fault, though this could be related to the other issues going on.

He verified the ABS module to be working via directly powering it, so eliminated that as a problem source. He states the issue is within the wiring harness. In order to fix the issue, the tech would need to pull the wiring harness, tear it down (physically separate the wires), find the fault, fix the fault, then put it all back together again.

There is no way you'd be able to power the ABS separately and expect anything to work differently. The main problem is the communications. You might be able to run separate wires for each shorted (or disconnected) wire, but you'd have to go through and check each associated wire to ensure you were replacing all of them. It might be one wire, but suggest it is more than one causing the issue(s).

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  • Thanks Paulster2. When he said “Direct powdered the module and verified com present” I took that to mean that if I direct power the abs module, the coms will start working again. I assumed the abs module gets ign from the fuse box and that was the broken wire
    – mikeg008
    Jan 1, 2023 at 20:03
  • @mikeg008 - I "think" by that he was checking to see if the ABS unit was working and that he's getting a signal directly from it. There's the main power, which is switched and fused. Then there's a signal which comes from the ECU which tells the ABS unit to turn on. I'm not sure by his notes if everything was working correctly when powered and turned on. I'm betting if all it was is the signal wire from the ECU to be at fault, he would have suggested just running a separate wire from the ECU to the ABS module. Jan 1, 2023 at 20:14

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