Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hello, and thank you for allowing me the opportunity to help you. If I am not online when you are, please allow me time to return. Can you tell me if all of these happen around the same time? Do you ever have trouble starting the vehicle?
no vehicle has no starting problems
and yes all symptoms seem to happen pretty much at the same time
I'm no mechanic but this just seems to scream a grounding problem to me.....but then again I'm no mechanic
Thank you. Most of the time this is either going to be a ground issue with the body control module or the module itself is failing. It is common on this vehicle. It may also be a problem within the ignition switch, but that is not as common. I would start by checking the grounds and then doing a voltage drop test on the ignition switch. Do you plan on fixing this yourself?
the monte carlo has a new ignition switch also just replaced in the last 60 days
I'd like to try if you can point me to the areas that i need to look and what tests i need to do
You need to check ground 201 and 203. They are shown in the pictures below. Let me know what you find. If you can locate the clicking noise as to the body control module then it may be the module.
The BCM is located under the drivers side of the dash.
ok I'll check....do I need to remove the plastic below the steering column to get up under the dash
Hey I found both grounds...they were a lot closer together than I was figuring....they both look secure, no busted or cracked wires
I had planned on having the instrument cluster tested/fixed. Something I'd never realized is there was always this scraping sound kind of at startup and I guess I always thought it was something to do with the hvac doors opening or closing. Turns out it's the small gauges on the left side of the cluster. This isn't normal is it?? I guess my point in all of this is I'm kind of waiting to hear if the BCM could be causing the low volt lights and gauges fluctuating or if that's seperate from the BCM...
Hi, glad to be of help. I have a differing opinion.
From the codes you listed, you most likely have a bad EBTCM.Many people have had EBTCM issues, and they tend to go bad on these cars.
Probe the 3 wires going to the flasher module, check for shorts to ground, shorts to voltage, grounds, opens, AND reference voltage. Check for corrosion at all terminal pin connections on EBTCM.
Check for corrosion on the Maxi-fuse terminals that may be causing a high resistance and verify there is 12 volts on both sides of the fuses.
The EBTCM circuit ties into the turn signals. Check or replace turn signal bulbs. The turn signal sockets are also known for going bad, so visually inspect the contacts on your turn signal socket to make sure there are no burn marks or meltedplastic in the housing. Flick the blinker on with the turn signal stalk and use a voltmeter to see what type of voltage you are getting at the bulb socket contacts. If all connections and reference voltages are good, replace EBTCM.
TRACTION CONTROL SYSTEM DESIRED TORQUE CIRCUIT
Traction Control System (TCS) uses Anti-lock Brake System
(ABS) in conjunction with PCM fuel and ignition controls tolimit
drive wheel slippage during acceleration.
You likely won't notice any drivability problems.
Desired torque signal Pulse Width Modulation (PWM) is less
than 5 percent or greater than 95 percent.
Check for faulty connection at EBTCM. (Electronic Brake and
Traction Control Module)
U1040 shows thatcommunications has been lost with the electronic brake control module.
This relay inside the EBCTM is what usually goes bad.
Here's some forum links:
So can I remove the EBCTM myself??
Does this need to be rebuilt or Can I just replace that relay??
Yes, it bolts to the BPMV. No you can't just replace that relay, it is an integral part of the EBTCM. Just make sure you get the correct module with traction control.
Seeing that U1040 code with the P1571 tells me the EBTCM is your problem.
You can try tapping on it for a temporary fix but here is the replacement procedure:
Electronic Brake Control Module (EBCM) Replacement Removal Procedure Notice:To prevent equipment damage, never connect or disconnect the wiring harness connection from the EBCM with the ignition switch in the ON position.
Important: Do not pry apart using a tool. Be careful not to damage BPMV surface.Important: Care must be taken not to damage the solenoid valves when the EBCM is removed from the BPMV.
Notice: Refer to Fastener Notice in Service Precautions.
Before you replace any parts or conduct any testing, first check the wiring harness. The harness passes under the front of the transmission side cover. GM reports that harness chafing can occur in that area because the powertrain flexes on its mounts. Check the harness for any signs of chafing. Next, examine the area near the A/C dryer canister where the ABS harness splits. The harness can chafe right at the dryer canister bracket. If you find chafing, remove the harness and repair the damaged insulation with heat shrinkable tubing.
Last night I sent the instument cluster and the ebctm to the speedometerrepairguy.com to get rebuilt. Once I figured out the four bolts were torq head and not hex it all come apart relatively easy. Now when I get this all back together just turn the key to on and then what?? does the car do it's own diagnostic's or is there some other surprise around the corner??.....and I'll do a double check on the harness, I looked it over when I was looking around yesterday.
Check ALL the EBTCM fuses and the main ground wire on the module.Until your confirm that the module has power and grounds there NO way you can say that the module isn't working.DTC U1040 Loss of Communications with TCS, That means the module is MOST LIKELY not getting power or has a poor or NO Ground.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes). Once the system has displayed all modules, it goes into the manual mode which allows selection of each module.If no codes are present in a given module, you will see No More Codes on the display. You may need to program the EBTCM but I don't think so in your case. If any codes come up, clear all codes and check again.
Okay, so I told you I sent both the instrument cluster and the ecbm to get tested/fixed. The instrument cluster was rebuilt but he couldn't rebuild the ebcm. He did tell me he tested it and it has faults. I called around our local salvage yards and found one and it was actually delivered to me today. What I received was the whole assembly not just the module. My question is can I just take the module off this on and put it on the one on the car or should I change out the whole thing??
Sounds good....I've got plenty to do without thinking I'm a mechanic....was just a little nervous because I keep hearing the reprograming word and was worried that the car would throw out a bunch of error codes