Please help! Alero threw these codes

09-08-2010, 04:35 PM
Hey guys:

So last winter i had my Trac control,ABS-LOCK, and service viechle soon light come on. well i bought an ABS cabable code reader (Equus 3150) and i got a slew of codes.

Left Rear Excessive Wheel Speed Sensor Variation
Excessive Wheel Speed Variation
Left Rear Wheel Speed Sensor Input Signal = 0
Right Front Wheel Speed Sensor Input Signal = 0
Left Rear Wheel Speed Sensor Circuit Open or Shorted
Right Front Wheel Speed Sensor Circuit Open or Shorted
DTC C1291 Set In Previous Ignition Cycle
Low Master Cylinder Pressure During Deceleration
Open Brake Lamp Switch Circuit During Deceleration

i got the definations from the website of the codereader.
by looking at it i believe the top 6 codes are due to the wheel hub assembly needing to be replaced, but what are the other 3( C1291-C1293).
Thanks guys.

09-09-2010, 06:30 PM
I hate to say this but that was probably a poor purchase decision. The codes and translation doesn't match or are inaccurate. The only real scan tool capable of reading GM Mark VI/Bosch ABS DTCs is a GM Tech 2 scan tool. The last 3 DTCs you are getting do not match what is in the GM Alero Factory Service Manual.

Have you checked the electrical connector to the Electronic Brake and Traction Control Module (EBTCM)? Clean, no corrosion and tight? Located driver's side front on the left part of the subframe.

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09-09-2010, 10:42 PM
I actully did some checking on google, and i found the gm service manual for brakes, and those codes were in there. this makes me even more confused than before i started all this.

09-11-2010, 04:32 PM
I found this website which seems to have the right ABS codes for the 1999-2000 Grand Ams and Aleros (Delco ABS-VI system):

C1292: Open Brake Switch Contacts When ABS Was RequiredOpen Brake Switch Contacts When ABS Was Required

I recently removed/cleaned replaced the BrakeSwitch and Cruise switch which are under the dash, held against the brake pedal to open/close when the pedal is depressed. You might want to check those two switches out...
Hope this helps.

09-11-2010, 04:41 PM
I am wondering if you have tried to clear the codes and drive the vehicle to see if it recodes?? You had mentioned that the codes set last winter?? That has been a few months ago! I bet if you clear them (assumining you haven't already done that) Some of those codes may go away altogether. Worth a try :runaround: Would hate to see you chasing ghost's!

09-13-2010, 08:49 AM
Definitely clear the codes and take it for a short ride.... see which codes come back. Only one bad wheel sensor can give you the ABS/Track OFF/ServiceVehcleSoon trio... search this site for numerous discussions on that. What year/engine etc do you have? I think Aleros switched from Delco ABS-VI to DBC 7 abs brake system in 2001; they have some over-lapping codes which mean different things depending on exactly what year/ABS system your car has.

09-13-2010, 08:00 PM
ok guys thanks for the input, i really apreciate it. Anyway i cleared the codes and now i get 2.... 1233 and 1234

09-13-2010, 09:24 PM
Cool that may simplify things a bit. Check all your wiring and connectors to those two sensors. Would seem to me it is more likely a issue with wiring or dirty connectors. Not often you would see two wheel speed sensors fail at the same time (never know though we are dealing with a GM product LOL) - I worked for Oldsmobile from 1990 to 1999, sad GM let them go..... :crying:

09-13-2010, 10:33 PM
How difficult would getting to those sensors be, also what would i look for as to how they are good, would i use an ohm reader or is their any other simple thing i could check.

09-14-2010, 10:19 AM
The sensors are part of each wheel bearing / hub assembly; to replace the sensor you have to replace the assembly. Not too difficult a job. But u should check out:

especially BNaylor's part which has typical ohms resistance measurements for the sensors. It can be sensor, or wiring.

If you have to replace a hub, check out: (
hope this helps

10-28-2010, 08:30 AM
Bet its gonna be the hub assy that will have to be changed. GM screwed us by making it all one assy. :banghead:

12-05-2010, 09:57 PM
Read this thread, I posted it a couple months ago, but it has a lot of info for this specific problem. I hope it helps. :)

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