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2003 Suburban ABS light issues

Discussion in 'General Chevy & GM Tech Questions' started by ElbowJoe, Aug 26, 2012.

  1. ElbowJoe

    ElbowJoe Member

    Hello.

    I have a 2003 1/2 Ton Suburban 5.3L Flex 4WD with 142,000 miles. I have an issue with the ABS light coming on when driving slow and hitting speed humps. An audible tone is heard (like the one that tells you a door is not closed (ding, ding, ding)) and the ABS light comes on. Typically when I turn off the vehicle and then re-start it the ABS light goes off but this is not always the case. It will also come on intermittently without the tones when first starting out but will shut off after moving a bit.

    So far, I have checked the engine-to-chassis ground straps (cleaned and re-seated), removed the front wheel ABS sensor cables, then cleaned and re-seated them along with the tone ring (after testing the resistance as outlined in the Chilton's manual - appeared normal), inspected the cables for wear and visually looked at the ABS module located under the drivers door for any obvious loose connections etc.

    I am thinking this is a grounding issue of some sort but would like some suggestions on how to better troubleshoot this. I am hoping it is not a problem with the ABS module.

    Any help would be appreciated. - Thanks!
  2. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    You might have a loose/broken wire at a wheel sensor. I'd check the front ones first.
  3. ElbowJoe

    ElbowJoe Member

    Thanks Ray. I will pull the front wheels off and give it another good look. I think I am going to check a couple of other ground points as well. I understand there is one under the battery and also check the ABS module wiring and grounds. This is one of those things that just drives me nuts!
  4. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    While your in there Joe, check the reluctor teeth for dirt and rust, clean if needed.
  5. ElbowJoe

    ElbowJoe Member

    OK. So for what it is worth, I have done the following and no longer have the issue:

    1) Removed both front wheels, calipers and caliper brackets. From here I was able to remove the ABS sensor wires. On this vehicle, the tone ring is enclosed in the casting and there is no way for it to get dirty etc. - unless the casting seals are compromised. This was NOT the case with my Suburban. I cleaned the magnetic pick ups on the ends of the wires (were not really dirty), cleaned the mounting surface, added some sealant to the base of the wire where it mounts to the casting and reseated them in place. (held with 5mm SHCS)

    2) Followed each wire up into the engine compartment (just above the suspension), unplugged it, inspected for corrosion and dirt and reseated 3-4X just to make sure they had good contact. (they were in good shape)

    3) Located the ABS module (under driver side frame near fuel filter) and inspected each electrical connector (there are 2) for corrosion and dirt. Although they looked good, I cleaned the surface of each wire spade lightly with a point file and re-seated the connectors.

    After assembling the front brakes it is important to pump them back up as I had to compress the caliper pistons slightly for easy re-assembly. Once I had brake pedal pressure, I was able to take a test drive. As soon as I was in motion, the ABS light went out and even after a thorough test drive hitting several speed humps and regular rough road sections as well as smooth road driving, I have not had the ABS light go back on and there have been no ding, ding, dinging of alarms. I have since driven the Suburban for about 150 miles with out issue.

    I am going to call this one fixed for now. I feel it may have been intermittent poor electrical connectivity on one or more of these connections.

    I hope this post help someone else as the "fix" was relatively easy and did not involve any replacement parts.
  6. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    Excellent, thanks for the update Joe.
  7. ElbowJoe

    ElbowJoe Member

    Follow up.

    A couple of days after my last post the issue re-surfaced along with a check engine light. This was simply too much of a coincidence for me. I decided to trace the wiring harness completely and locate all grounds and connections. As it turns out the grounds seem to have been the issue all along.

    I located a total of 6 grounds. One runs from the firewall to the back of the engine block, one runs from the firewall to the hood, one is located under the battery and runs from the battery to the frame, two are located near the fuel filter (underneath on the frame on drivers side between front are rear seats) and the last one runs from the fuel filler neck to the frame. All were in pretty good shape except tor the two near the fuel filter. I cleaned all and re-seated coating well with di-electric grease (especially the ones near the fuel filter). I used a dremel with a brass brush.

    As mentioned, I also checked and re-seated all cable connectors starting in the fuse box under the hood and worked my way along the wiring harness. These all looked pretty good so I don't think they were the issue.

    After this procedure, the ABS light went out immediately and has not returned after several hundred miles and a week and a half of daily driving. The check engine light had to be reset (O'Reilly Auto Parts allows you to use a code reader for free) and once cleared, did not return. (I did check the codes and their possible issues as well and addressed separately. O2 sensor and knock sensor low voltage related.)
  8. Bighornkid

    Bighornkid Member 2 Years 100 Posts

    Thanks for the info, Joe. I'll keep it mind in case my 04 has similar issues.

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