Member Since: 06 Feb 2020
Location: california
Posts: 5
HDC triggers instant faults when brake applied
If I get the car all settled and happy, then point it down a slight hill, foot brake applied, engage HDC, start rolling and I get all of the faults and car lowers to ground (I can hear ABS pump run for a second and some jerky brake action for a second) (but still reports standard ride height).
OBDII reports from the following modules:
Ride Level Module U0416 (invalid data vehicle dynamic control module)
Terrain Module U0416 and U0421 (invalid data from Ride Level)
ABS/Dyn Module reports C1A00
Instrument cluster reports U0159 and U0132 (but these two faults tend to appear frequently and separately form the above).
Turn off HDC, park car, clear codes and all is well unless HDC is engaged again or occasionally it will happen for no reason.
Has new compressor, new relay, all new air valves, new front struts, new battery, all fuses good, new OEM brake switch and new OEM brake lights, new ABS wheel sensors, new YAW sensor, new ride height sensors, wiring in left front LHD wheel well is perfect. Car never wrecked. Never in flood. No salt. Did both A pillar sunroof drain fixes when we did the rotten wire for the remote in the right rocker panel about 4 years ago.
What am I missing?????? Going crazy with this thing. Rewards may be offered
6th Feb 2020 8:32 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
I guess it’s the abs pump.
And if you needed the abs to work it wouldn’t.
6th Feb 2020 9:36 pm
towhook
Member Since: 06 Feb 2020
Location: california
Posts: 5
I replaced the ABS pump, did my best to manually bleed the lines but now I get several amigo lights. No DTCs from ABS/Vehicle Dyn Control but I get invalid data from ABS reporting from Ride Level and Terrain Response CM. I assume it is coded to the VIN and that is the error. IDK. I guess it is a trip to the steelership or steeler indy to sprinkle magic dust on the bloody thing.
Just ordered GAP iid tool with free extra key. Hopefully that will let me do these things. I heard that they charge about $35 for software downloads to program, for example, the rear diff locking motor, the EAS Module, ABS Module, etc. So, the tool with the software adds is about $650. I hope it works.
7th Feb 2020 6:55 pm
towhook
Member Since: 06 Feb 2020
Location: california
Posts: 5
GAP tool arrived. Tried the power bleed on brakes. It failed. So, the replacement abs unit appears also bad. Went and pulled it apart. Found that someone had already been in it and the solenoids were fused to the solenoid valve shafts. Prior hack just shoved it back together and that was a failure. Opened original pump. Abs motor bad.
Waiting for yet another abs unit. SRB500163
There are other faults but I can't get anywhere until the abs issue is resolved. I will update asap
16th Feb 2020 12:59 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4580
I have had nearly a dozen ABS pump motors fail over many years because of exposure to water / moisture. Water ingress is unusual for the D3/4 given its well shielded location, but there may be an other factor / fault that caused the failure.
New pump motor should sort your problem given the faults / DTC'S you have reported. Make sure your battery is at full charge when you fit the new motor/ABS unit, and clear the codes before and after first test. Then road test again
The other U codes should vanish once the motor issue is sorted!yµ (idµ - eAµ) ψ=mψ
16th Feb 2020 2:06 am
towhook
Member Since: 06 Feb 2020
Location: california
Posts: 5
Thanks. This car has been a nightmare. Wife wants me to call wrecking yard. Jesus. New tires, new rims, new rotors, new air struts, all new air valves, new compressor, new AGM battery, new extra keys, new radiator, new rear diff locking motor, newer trans motor unit, new trans fluid and metal pan conversion, V8 HSE Lux model black on black California car, no wrecks or even door dings.
The original abs unit apparently had that motor failure you mention. If you engage HDC, it would cause a failure. The replacement, I had a shop to the switch out but they said something was stuck so they could not change it. I changed it anyway and got a stuck valve code. It would not run the motor with the power bleed. Removed it. Opened it and realized that the shop literally tore the solenoids away since they were stuck from mild rust. Tried power bleed on original unit and got no motor at all. That irritates me because I brought it to a shop about 2 years ago to power bleed after I put in a new master cylinder. They said it was fine. After that the problems started -- with the abs. There were/are other problems too but still. Monkey shops.
16th Feb 2020 2:16 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
don't you have enough good bits to make a good one out of ?
At least you will have seen inside it
16th Feb 2020 11:24 am
towhook
Member Since: 06 Feb 2020
Location: california
Posts: 5
I wish. I have the ebay unit that a shop "tried" to take apart and ended up ripping the wires from the solenoid coils, etc. I think the motor and valve section may be ok but I am not sure. Then I have the original unit that clearly has a motor problem BUT I believe that same shop took it apart too and I suspect it also has damage that I would not be able to repair on the board. I will try and pull it apart tomorrow - carefully and see. I did find yet another one on ebay but it will not be here for several days.
That abs problem is keeping me from sorting out any other issue or setting the correct ride height calibration. Hopefully once the ABS is corrected, it will eliminate what appears to be several cascading faults.
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