Ok
BCM replaced and for the 10 minute drive home I experienced NO issues! I will test more thoroughly during the weekend and post results. But so far so good!

 

I'll find out tomorrow when we go on a trip if the light comes on again.

 

Adjusted tires size via HP Tuners... SAH still occurs randomly. Dealership her I come.

 

Well after getting a Tech2 I started getting the SAHS again. It got to where every time that I drove the car I got this message within a mile or so from home. I started checking the codes and each time it would show that the BPPS was throwing a code C0161. Ordered a new BPPS and replaced and calibrated with the Tech2, and after taking it out for a test ride got the same code within 2 Miles from the house. After searching different post decided to replace the EBCM just the electronic portion, it came in on Saturday got it put in and have taken it out on three different occasions and everything appears at this point to working properly. I really appreciate people on this forum for all the help....Chevy Dave....Bill Dearman just to name a couple, these guys are a Godsend for DIY's.

 

Anymore issues after replacing the BCM? I have had the EXACT same issues for a few months now including the same codes. Just replaced the sensor with no luck.

 

After I Replaced The Module Everything Seems To Be Working Fine So Far. Did You Replace The Bpps If So That Was My First Move Before Changing The Ebcm.

 

I have replaced the BPPS. Next step sounds like the EBCM. Did you replace it with a dealer part? Thanks.

 

The brake pedal position sensor sends an analog signal to the BCM which then sends a digital signal to the EBCM across the GM LAN. A code like C0161 does not tell you to replace the BPPS but does tell you there is something wrong with that signal or in the signal path from the sensor to the EBCM. In this case the sensor could be the problem, the wiring and connectors between it and the BCM could be the problem, the BCM could be the problem, the EBCM could be the problem or the Instrument Panel Module could be the problem since the sensor gets its 5 volt reference from it. It isn't likely the GM LAN is the problem since there more than likely be really major issues with the car. As for the C0161 diagnostic procedure there is nothing that tells a mechanic to replace the sensor. Here is the diagnostic procedure which includes comments about what may cause the code to occur including certain driver actions that can cause it.

DTC C0161
Diagnostic Instructions
• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC C0161 00: Antilock Brake System (ABS) Brake Switch/Sensor Circuit not Plausible.

Circuit/System Description
The brake pedal position (BPP) sensor is an input to the body control module (BCM). The BCM then sends a serial data message to the electronic brake control module (EBCM) and other electronic control modules. The BPP sensor is a potentiometer type sensor with a 5-volt reference circuit and a low reference circuit. The instrument panel module (IPM) supplies the 5-volt reference to the BPP.

Conditions for Running the DTC
• The ignition is ON.
• The vehicle speed is greater than 16 km/h (10 mph).
• The ignition voltage is greater than 9.5 volts.

Conditions for Setting the DTC
• The brake pedal is sensed as applied.
• The vehicle speed is greater than 40 km/h (25 mph).
• The vehicles acceleration exceeds 8 km/h per second (5 mph per second).
This means the car has sensed the brake pedal being applied while accelerating. Under the 2 conditions mentioned above.

• Brake pedal is not applied.
• Master cylinder pressure is greater than 150 psi.
• The vehicle speed is greater than 24 km/h (14 mph).
• The vehicles deceleration exceeds 11.5 km/h per second (7 mph per second).

This means the car senses the brake pedal isn't being applied under the 3 conditions mentioned above. The master cylinder pressure refers to the brake pressure sensor output which would indicate a conflict between two different sensors. One indicating the brakes aren't being applied and one that indicates they are being applied.

Action Taken When the DTC Sets
The ABS/TCS/ESC remains functional. (Interesting comment which might mean this isn't a big deal other than a light on the IP.)

Conditions for Clearing the DTC
• The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
• The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
The DTC C0161 00 can be set if the vehicle has been driven with the brake applied during acceleration.

Reference Information
Schematic Reference
Antilock Brake System Schematics

Connector End View Reference
Component Connector End Views

Description and Operation Reference
ABS Description and Operation

Electrical Information Reference

• Circuit Testing
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Connector Repairs

Scan Tool Reference
Control Module References

Circuit/System Verification
With the ignition ON, use a scan tool to display DTCs for the BCM.

⇒ If DTC C0277 or C0278 are present, go to Diagnostic System Check - Vehicle.

⇒ If no DTCs are present, go to Diagnostic Aids.

Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Notice right at the beginning the only thing the code indicates is the signal isn't plausible. That means it is the wrong value for the conditions that exist when the test is run. This pretty much leaves it to the mechanic to find using the test equipment (including the Tech 2, a DVM, signal break out boxes, etc) and a methodical diagnostic process to eliminate the possible sources of the error. That isn't particularly easy to do if the car comes into the shop without an active failure code since everything is working as it should be working. If it ain't broke you can't fix it and shouldn't try to fix it.

Bill

 

Thanks Bill! I have followed that same procedure as it is listed in my alldata account. I have also allowed two dealerships to diagnose the issue and according to their replacement plan they call the BPPS and then the EBCM. I started receiving these issues after the dealer installed my plastic comb to fix the recall. So, the technician in me has always gone back to what was done last or at least back to the area the work was done. That said, I've checked all the connections under the kick plate, read voltages, tested wires for possible breaks, read DTCs, and verified as best as I can that the plug / connectors were all solidly seated. The unfortunate part is the technician in me is having an issue pulling the trigger on a $700+ part just to see it return. But hey, if I DIY then I've saved myself the labor charges. Thanks for the help guys.

 

I Actually Found One On Ebay Off Of A 2008 With 21000 Miles On It. I Was Like You A Little Apprehensive About Spending That Kind Of Money And Actually Got The Whole ASsembly Got $240 Shipped. I Only Changed The Electronic Portion Of The EBCM Didn't Want Deal With All Those Brake Lines And Fluid Bleeding And Such. I Talked To The Guy At Absfixer.Com And This Was A Common Problem On The C5's Which He Is Able To Repair But He Doesn't Do Repairs On The C6's. Good Luck With Your Project.

 

I understand the hesitation to replace an expensive module without being able to prove it is bad. It might be worthwhile to drive the car some more and when the failure occurs again note the driving condition at that point. Were you accelerating or decelerating? Foot on the brake or not?

Bill

 

I replaced the EBCM this weekend. I have been trying to find out just what is needed as far as programing after the install. ALLDATA indicates the system must be programmed but there are no steps or procedures to do so. Is it just a BPPS reprogram or something else?

 

I did actually change the BPPS and it did have to be programmed. I had purchased a Tech II and was able to program/calibrate the BPPS. But after changing the EBCM the SAHS light stayed on as soon as I cranked the car. I took the car out for a ride after changing the unit. After making a stop and starting the car back up the SAHS light went off and seems to be fixed now. Hope this helps.

 

Just wanted to follow up on the post that I started over a year ago hoping this will help someone that is experiencing SAH system problems. I first replaced the BPPS and the same problem persisted, after that I replaced the ECBM that I found used on Ebay and it appeared to working properly but after a few weeks the problem came back. I didn't want to take it to the dealership and after much searching a guy recommended a small shop in town. I took it in and he has a connection with AC Delco online. He hooked up his tech2 to my car and had a ethernet connection from the tech2 to his computer which he was able to go on line to AC Delco and retrieve an update for the ABS system. He downloaded this to my car which configured the used EBCM to my car and now after driving it for over the last month or so with no Service Active Handling System messages popping up on the display and the traction control switch is working now which it hasn't worked in over a year. Hope this helps.

 

Thanks for the update! I have been trying to get to the bottom of my SAHS message as well and have replace AND calibrated the BPPS. I started looking back to when the issue first started. It was AFTER I was in the fuse box behind the passenger foot board. I was getting the C0161 code and a C0561. The C0561 points to a "serial data" problem. I also noticed I would get the C0561 message when my over 6ft son would ride shotgun and stretch out his "sasquatch" legs. I went over every connection to the fuse box and BCM, reseating the data cables. So far, no issues but it has only been a couple of weeks. I have also kept folks from completely stretching out their legs when they ride. If it comes back I to have EBCM that I scooped off of ebay. That will be next.

 

Hope that works for you because changing the EBCM is a major under taking. I finally went to the Automotive store an purchased a couple of extensions and a 1/4" swivel's that without them I would still be trying to put it back on.

 

Sounds like you need to pull the foot panel out and take a look at how the wiring harnesses to the BCM are routed. If foot pressure is causing the problem that means one of the harnesses or a harness connector or the BCM could have an intermittent connection. Not easy or cheap to fix but if a harness can be rerouted so foot pressure isn't causing something to deflect you might be able to get by without a repair. Be careful since you could also make it worse by causing a solid failure.

Bill

 

I figured I might throw in an update on mine which is basically on the Service Active Handling thread and hopefully not too off topic. I also had these messages and codes pop up more and more often. I have an 08 and except for the starter, just about all of the problems that I have had been due to bad connectors or sensors.

One of the early posts said to put in the plastic comb. I had that, and do not have a telescopic steering wheel, but that connector does get corroded.

The basic fix is to take it apart, clean it and put it back together. There is a very good and detailed set of instructions on how to do it posted earlier. FYI, I found that the Auto Zone materials do not work. Go to an electronics specialty store and buy a high quality contact cleaner and high quality dielectric grease. Start with this $20 cleanup before buying expensive brake modules or steering wheel sensors.