C0550: A chassis control module reports an internal fault
ECU performance (chassis) / EBCM malfunction
Severity: Inspect soon
A reference source says to have this code diagnosed promptly, and GM bulletins tie it to ABS, stability, power steering and four-wheel-drive faults, so book a check soon.
C0550 in short
C0550 means a chassis control module has reported an internal fault. On GM it is usually the ABS brake module, but bulletins also list the 4WD transfer case module and power steering faults. Low battery voltage, a chafed harness or software can be behind it. Get it checked soon.
A reference source defines C0550 as an ECU performance fault in the chassis: the module itself says it is not working correctly. The module is not named by the code.
GM bulletins show the code on ABS and StabiliTrak, on four-wheel-drive systems where the transfer case control module sets it, on some power steering systems and on tire pressure systems.
Several GM bulletins point to causes outside the module: low battery voltage on crossovers, a harness chafed on a transmission mount, and software that needs reprogramming on 2003 trucks.
Most likely causes
Cause 1: Weak battery or low system voltage
Supported by vehicle data- Why it ranks here
- GM bulletin PIP-4478A says various concerns may be related to a low battery when C0550 sets with all wheel drive inoperative. The bulletin status is unverified.
- What would change this
- Rises if the battery tests weak or the car cranks slowly. Falls if the battery and charging are healthy.
Cause 2: Chafed wire harness to the brake module
Supported by vehicle data- Why it ranks here
- GM PIT-4756 says the harness to the EBCM can chafe on the transmission mount or a bracket on Equinox, Torrent and Vue.
- What would change this
- Rises if the harness shows rub marks. Falls if it is clean.
Cause 3: Brake module software that needs reprogramming
Supported by vehicle data- Why it ranks here
- GM bulletin 04-08-49-006A says to reprogram the EBCM for C0550 on 2003 Yukon, Escalade and Avalanche. Unverified.
- What would change this
- Rises if a dealer finds an update for the VIN. Falls if software is current.
Cause 4: Another module setting the code (4WD or power steering)
Supported by vehicle data- Why it ranks here
- GM bulletins show the transfer case control module setting C0550 on 2004 TrailBlazer-family SUVs, and C0550 listed among power steering codes on compact cars.
- What would change this
- Rises if a 4WD or power steering light is on with the ABS light. Falls if only ABS or stability lights are on.
Cause 5: Defective tire pressure sensor (Aveo)
Possible — needs testing- Why it ranks here
- A GM bulletin for the 2008-2009 Aveo says a defective tire pressure sensor can be one cause of C0550 with the tire pressure light on.
- What would change this
- Rises if the tire pressure light is on. Falls if it is not.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all codes from every module and note which warning lights are on (ABS, 4WD, power steering, tire pressure).
IfOnly a tire pressure light is on with C0550 on an Aveo
It meansCheck the tire pressure sensors.
IfA 4WD or power steering light is on
It meansAnother module may set the code.
Points to: Another module setting the code (4WD or power steering)
IfABS or stability lights are on
It meansCheck voltage and wiring.
Step 2: Have a shop test the battery and charging system, then inspect the harness to the brake module for rub marks.
Warning:Brake, stability and wiring checks need scan tools and a lifted vehicle. Let a shop do this.
IfVoltage is low
It meansFix the battery or charging fault first.
IfHarness damage
It meansRepair the harness.
IfBoth are good
It meansAsk whether a software update applies.
Symptoms
- ABS or service stability light on
- Service 4WD or all wheel drive light on
- Power steering message on some compact GM cars
- Stability and ABS not working Gets more serious: stop and have it checked.
How to fix
This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.
Parts and cost context
- Brake system control module (ABS module):Check voltage, wiring and software before replacing the module. Labor varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
ChevroletYour car
2004 · Trailblazer
Supported by vehicle dataGM bulletin: C0550 can be set by the transfer case control module on these 4WD SUVs.
2003 · Avalanche
Supported by vehicle dataGM bulletin: reprogram the EBCM for C0550 on these 2003 trucks.
2005–2008 · Cobalt
Supported by vehicle dataGM bulletin lists C0550 among power steering codes on these compact cars.
2006–2008 · HHR
Supported by vehicle dataGM bulletin lists C0550 among power steering codes on these compact cars.
2008–2009 · Aveo
Supported by vehicle dataGM bulletin: tire pressure light with C0550 on the 2008-2009 Aveo; a bad tire pressure sensor can be a cause.
2007–2011 · Equinox
Supported by vehicle dataGM bulletin: harness chafe to the brake module can set C0550 on these crossovers.
030421006Status unverified
Service 4WD light, no communication with TCCM, C0550
2004trailblazer · NHTSA 10004367
C0550 set in the transfer case control module with 4WD not working.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
040849006A (chevrolet)Status unverified
Service message with C0550 set, reprogram EBCM
2003avalanche · NHTSA 10008686
The summary says to reprogram the EBCM for C0550 on the 2003 Yukon, Escalade and Avalanche.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
070232007 (chevrolet)Status unverified
Power steering inoperative with C0550 among the codes
2005–2008cobalt, hhr · NHTSA 10022958
Diagnostic tips for a power steering message listing C0550 with C0176, C0475, C0476, U2105 and U2107.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIC-4955AStatus unverified
Tire pressure light with C0550
2008–2009aveo · NHTSA 10026647
A defective tire pressure sensor can be one cause.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIT-4756 (chevrolet)Status unverified
ABS and StabiliTrak lights with C0550, C0186, C0196 and others
2007–2009equinox · NHTSA 10028186
The wire harness to the EBCM can chafe on the transmission mount or a bracket.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP-4478A (chevrolet)Status unverified
All wheel drive inoperative with C0550
2007–2011equinox, traverse · NHTSA 10034431
Various concerns may be related to a low battery.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
GMCYour car
2004 · Envoy
Supported by vehicle dataGM bulletin: C0550 can be set by the transfer case control module on these 4WD SUVs.
2003 · Yukon
Supported by vehicle dataGM bulletin: reprogram the EBCM for C0550 on these 2003 trucks.
030421006 (gmc)Status unverified
Service 4WD light, no communication with TCCM, C0550
2004envoy · NHTSA 10004367
C0550 set in the transfer case control module with 4WD not working.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
040849006AStatus unverified
Service message with C0550 set, reprogram EBCM
2003yukon · NHTSA 10008686
The summary says to reprogram the EBCM for C0550 on the 2003 Yukon, Escalade and Avalanche.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP-4478AStatus unverified
All wheel drive inoperative with C0550
2007–2011acadia, terrain · NHTSA 10034431
Various concerns may be related to a low battery.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
BuickYour car
2004 · Rainier
Supported by vehicle dataGM bulletin: C0550 can be set by the transfer case control module on these 4WD SUVs.
030421006 (buick)Status unverified
Service 4WD light, no communication with TCCM, C0550
2004rainier · NHTSA 10004367
C0550 set in the transfer case control module with 4WD not working.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP-4478A (buick)Status unverified
All wheel drive inoperative with C0550
2008–2011enclave · NHTSA 10034431
Various concerns may be related to a low battery.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
CadillacYour car
2003 · Escalade
Supported by vehicle dataGM bulletin: reprogram the EBCM for C0550 on these 2003 trucks.
040849006A (cadillac)Status unverified
Service message with C0550 set, reprogram EBCM
2003escalade · NHTSA 10008686
The summary says to reprogram the EBCM for C0550 on the 2003 Yukon, Escalade and Avalanche.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
SaturnYour car
2003–2007 · Ion
Supported by vehicle dataGM bulletin lists C0550 among power steering codes on these compact cars.
070232007Status unverified
Power steering inoperative with C0550 among the codes
2003–2007ion · NHTSA 10022958
Diagnostic tips for a power steering message listing C0550 with C0176, C0475, C0476, U2105 and U2107.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIT-4756 (saturn)Status unverified
ABS and StabiliTrak lights with C0550, C0186, C0196 and others
2008–2009vue · NHTSA 10028186
The wire harness to the EBCM can chafe on the transmission mount or a bracket.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP-4478A (saturn)Status unverified
All wheel drive inoperative with C0550
2007–2009outlook, vue · NHTSA 10034431
Various concerns may be related to a low battery.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PontiacYour car
2007–2008 · G5
Supported by vehicle dataGM bulletin lists C0550 among power steering codes on these compact cars.
2005–2006 · Pursuit
Supported by vehicle dataGM bulletin lists C0550 among power steering codes on these compact cars.
2007–2009 · Torrent
Supported by vehicle dataGM bulletin: harness chafe to the brake module can set C0550 on these crossovers.
070232007 (pontiac)Status unverified
Power steering inoperative with C0550 among the codes
2005–2008g5, pursuit · NHTSA 10022958
Diagnostic tips for a power steering message listing C0550 with C0176, C0475, C0476, U2105 and U2107.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIT-4756Status unverified
ABS and StabiliTrak lights with C0550, C0186, C0196 and others
2007–2009torrent · NHTSA 10028186
The wire harness to the EBCM can chafe on the transmission mount or a bracket.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
PIP-4478A (pontiac)Status unverified
All wheel drive inoperative with C0550
2007–2009torrent · NHTSA 10034431
Various concerns may be related to a low battery.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
Sources and review
- OBD Code C0550
- GM 07-02-32-007: power steering inoperative or hard to turn, C0176, C0475, C0476, C0550, U2105, U2107 (Ion, Cobalt, HHR, G5)
- GM PIP-4478A: all wheel drive inoperative with DTC C0550 (2007-2011 Acadia, Enclave, Outlook, Equinox, Traverse and others)
- GM PIT-4756: ABS and StabiliTrak lights on, U0121, C0550, C0186, C0196, C0710, C0252 (2007-2009 Equinox, Torrent, Vue)
- GM 04-08-49-006A: service message with DTC C0550 set, reprogram EBCM (2003 Yukon, Escalade, Avalanche)
- GM 03-04-21-006: service 4WD light, 4WD inoperative, no communication with TCCM, DTC C0550 (2004 TrailBlazer family)
- GM PIC-4955A: tire pressure monitor light on, C0550 (2008-2009 Aveo)
- GM 04-05-25-002B: ABS light on, C0265, C0201, U1041 and/or loss of communication with the brake module
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error