C1255 EBTCM Internal Malfunction
Thread Starter
Burning Brakes
Joined: May 2007
Posts: 1,078
Likes: 5
From: Denver, North Carolina
C1255 EBTCM Internal Malfunction
I have noticed lately that after a 'spirited' drive I have a C1255H code. I am not getting any ABS or TC warning lights or messages on the DIC, just after the drive I will pull my codes and there it is. I reset it and as long as I drive 'normally' there will be no more codes thrown. But as soon as I run through the gears pretty hard...there it is again. I have done a search and its related to the EBTCM. I want to know if this is a serious problem or it can be ignored for now. If I hadn't pulled up the code, I would never have known there to be a problem - all seems well.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
C1255 - Internal EBCM malfunction
C1255 indicates an "Internal Malfunction" within the EBCM. You should read Bill Curlee's sticky at the top of this forum to learn about cleaning the ground points in the car. The good news is for a lot of people, cleaning the grounds for the EBCM clear this problem. If that doesn't fix it, you need to give the folks at ...
http://www.absfixer.com
and get their advice on getting this repaired ... or you can go to the stealership and pay $1k or more for them to "fix" it ....
http://www.absfixer.com
and get their advice on getting this repaired ... or you can go to the stealership and pay $1k or more for them to "fix" it ....
Le Mans Master
Joined: Mar 2002
Posts: 8,466
Likes: 51
St. Jude Donor '17
so ebcm and ebtcm are the same when talking about this repair???
Electronic Brake Control Module (EBCM)
Location - Mounted with brake pressure modulator valve on the top of the left front frame rail
In the attached diagram, the EBCM is #2.
Description of what the EBCM does:
Electronic Brake And Traction Control Module
The EBCM/EBTCM performs the following primary functions:
Detects wheel slip tendencies
Detects wheel speed differences
Controls the brake system while in the antilock or traction control mode
Controls the Electronic Brakeforce Distribution (EBD)
Monitors the system for proper electrical operation
The EBCM/EBTCM also controls the display of the ABS and traction control DTCs while in diagnostic mode. The EBCM/EBTCM continuously checks the speed of each wheel in order to determine if any wheel is beginning to slip. If a wheel slip tendency is detected, the EBCM/EBTCM commands the appropriate valve positions to modulate the brake fluid pressure in some or all of the hydraulic circuits. This action prevents wheel slip and provides optimum braking. The EBCM/EBTCM continues to control pressure in the individual hydraulic circuits until a slipping tendency is no longer present. The EBCM/EBTCM continuously monitors the ABS/TCS for proper operation. If an error is detected, the EBCM/EBTCM can disable the ABS/TCS and turn on the ABS or TCS OFF Indicators in the IPC.
Electronic Brake Control Module (EBCM)
Location - Mounted with brake pressure modulator valve on the top of the left front frame rail
In the attached diagram, the EBCM is #2.
Description of what the EBCM does:
Electronic Brake And Traction Control Module
The EBCM/EBTCM performs the following primary functions:
Detects wheel slip tendencies
Detects wheel speed differences
Controls the brake system while in the antilock or traction control mode
Controls the Electronic Brakeforce Distribution (EBD)
Monitors the system for proper electrical operation
The EBCM/EBTCM also controls the display of the ABS and traction control DTCs while in diagnostic mode. The EBCM/EBTCM continuously checks the speed of each wheel in order to determine if any wheel is beginning to slip. If a wheel slip tendency is detected, the EBCM/EBTCM commands the appropriate valve positions to modulate the brake fluid pressure in some or all of the hydraulic circuits. This action prevents wheel slip and provides optimum braking. The EBCM/EBTCM continues to control pressure in the individual hydraulic circuits until a slipping tendency is no longer present. The EBCM/EBTCM continuously monitors the ABS/TCS for proper operation. If an error is detected, the EBCM/EBTCM can disable the ABS/TCS and turn on the ABS or TCS OFF Indicators in the IPC.
Last edited by Got uid0; Oct 28, 2007 at 08:46 PM.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Yup ... the Electronic Brake Control Module is also referred to as the Electronic Brake and Traction Control Module. Both terms are listed in the Service Manual Section called "Abbreviations and Meanings" ... the manual generally uses EBCM as the abbreviation .... but either is valid for a C5 Corvette.
Burning Brakes
Joined: Jan 2006
Posts: 1,170
Likes: 27
From: Magnolia Greens NC
This procedure may help..
The EBCM sits between the engine and radiator. The EBCM is on the left with the large wire harness coming into it and the sticker on top. The Brake Pressure Modulator Valve (BPMV) in on the right with the brake lines coming out. The EBCM is a dry module, meaning that you can change it out without having to worry about bleeding the ABS system. All of the brake fluid is contained within the BPMV. The coils fit over small spools that have valves inside them. The valves are operated by an electromagnetic field supplied by the coils.
Start by doing a quick visual inspection of the wires. If there are any obvious signs of damage, you've likely found the problem. One member had a problem with the wires rubbing the serpentine belt
Also check to make sure the wire harness has a good connection. If the connection appears solid disconnect it (see step 3 in the replacement instructions below) check the pins to ensure that they have not been bent or damaged in any way. If there is any sign of corrosion, clean it off. Once everything looks good, reseat the harness.
Next, let's move on to the grounds. The EBCM is grounded to the chassis on the left frame rail, just forward of the engine. It's the Black box . As you can see, it's real easy for dirt and moisture to get in that area which isn't exactly good for electronic components. Even if you never drive your car in the rain, it'll still get wet when you wash it, and that could be enough
Start by unbolting the chassis ground, then take the chassis ground connector apart.
Corrosion that can build up in the ground connector. Clean it up with a wire brush before putting it back together. Also clean off the chassis and bolt to make sure you've got a good clean ground.
If you are having any other electrical issues, it's a good idea to check the grounds.
At this point, we know all of the wires are good, but for some reason enough voltage is not getting to the system. It is possible that your battery is not functioning properly. If your battery is a couple of years old, has been drained and recharged a couple of times it might be a good idea to go ahead and replace your battery. This is a long shot for EBCM issues, but I think it's worth a shot before spending dollars for a EBCM and you're going to have to replace it eventually anyways. Old batteries can cause a variety of minor electrical issues and you likely have a bunch of history codes for minor issues if the battery is causing the problem.
Now on the EBCM itself. If the electrical contacts inside the relay are dirty or burnt, the vibration from striking the module may change the symptoms or may clear them up for a while. This is by no means a fix or a cure all, in fact it could make it worse or it may not do anything, it's just something to try. Use a small plastic hammer or something similar, lightly tap the front of the EBCM on the lower right corner of the module.
At this point, You've got to additional possibilities. Replace the EBCM or repair the EBCM . The service manual calls for you to measure the resistance between each pump motor control circuit and the housing of the BPMV, if that checks our okay, you replace the EBCM if not you replace them both. Since most people do not have the equipment to do this the best we can do is to replace the EBCM. If that doesn't work, you'll have to go back and replace the BPMV.
The procedure for removing the EBCM is very simple. The only special tool you need is a T-20 torx screw driver. I have a Craftsman tool set that has a 1/4" drive screwdriver with and adapter for many different size bit. Unfortunately, the adapter was to long to fit between the EBCM and water pump, so I purchased a set of Craftsman 5 pc. torx screwdriver set that worked fine. A flathead screwdriver may also be needed to pry apart the EBCM from the BPMV
1 - make sure the car is off.
2 - you will probably need to remove the airbridge to get to the EBCM.
3 - remove the wire harness by first removing the white plastic clip that locks it in place (I cut it off and replaced it with a zip-tie) , then lift gray handle and pull back on the wire harness . At this point, you will be able to see the second wire connection that is removed by pulling down .
4 - The service manual call for you the remove the 2 insulator nuts that hold the BPMV to the brackets and lift the EBCM/BPMV out of the bracket. I do not think this step is necessary because there is plenty of room while it is still in the bracket and you do not gain much additional clearance since the brake lines restrict the movement.
5 - Remove the 6 T-20 torx screws connecting the EBCM and BPMV - 1 on each corner and 2 on the sides .
6 - "Separate the EBCM from the BPMV by gently pulling apart until separated" - I should start laughing here, but it's not that funny. It's been my experience that anytime the instructions call for you to do something gently, nothing gentle is going to work. In this case, I had to use a flathead screw driver to brake the seal. Once it moved a little, the rest was easy. In addition to the rubber seal, each of the 12 holes have a peg in them from the BPMV. Don't go crazy, but be prepared to force them apart.
7 - At this point, you send it to ABS FIXER and all you've got to do is put it all back together (by the way, you can safely continue to drive your car without the EBCM, just remember that your electronic driving aids are no longer functioning so you should adjust your driving habits accordingly) When you get it back,push the repaired EBCM onto the BPMV.
8 - Replace the 6 T-20 torx screws
9 - reconnect the wire harness
10 - put the intake back on
An alternative to buying a new one is to have your original rebuilt.
For EBCM repair/replace
Call Brandon
877-648-7530 at ABS FIXER
or: www.absfixer.com
$150. plus UPS....warranted as long as You own it
Start by doing a quick visual inspection of the wires. If there are any obvious signs of damage, you've likely found the problem. One member had a problem with the wires rubbing the serpentine belt
Also check to make sure the wire harness has a good connection. If the connection appears solid disconnect it (see step 3 in the replacement instructions below) check the pins to ensure that they have not been bent or damaged in any way. If there is any sign of corrosion, clean it off. Once everything looks good, reseat the harness.
Next, let's move on to the grounds. The EBCM is grounded to the chassis on the left frame rail, just forward of the engine. It's the Black box . As you can see, it's real easy for dirt and moisture to get in that area which isn't exactly good for electronic components. Even if you never drive your car in the rain, it'll still get wet when you wash it, and that could be enough
Start by unbolting the chassis ground, then take the chassis ground connector apart.
Corrosion that can build up in the ground connector. Clean it up with a wire brush before putting it back together. Also clean off the chassis and bolt to make sure you've got a good clean ground.
If you are having any other electrical issues, it's a good idea to check the grounds.
At this point, we know all of the wires are good, but for some reason enough voltage is not getting to the system. It is possible that your battery is not functioning properly. If your battery is a couple of years old, has been drained and recharged a couple of times it might be a good idea to go ahead and replace your battery. This is a long shot for EBCM issues, but I think it's worth a shot before spending dollars for a EBCM and you're going to have to replace it eventually anyways. Old batteries can cause a variety of minor electrical issues and you likely have a bunch of history codes for minor issues if the battery is causing the problem.
Now on the EBCM itself. If the electrical contacts inside the relay are dirty or burnt, the vibration from striking the module may change the symptoms or may clear them up for a while. This is by no means a fix or a cure all, in fact it could make it worse or it may not do anything, it's just something to try. Use a small plastic hammer or something similar, lightly tap the front of the EBCM on the lower right corner of the module.
At this point, You've got to additional possibilities. Replace the EBCM or repair the EBCM . The service manual calls for you to measure the resistance between each pump motor control circuit and the housing of the BPMV, if that checks our okay, you replace the EBCM if not you replace them both. Since most people do not have the equipment to do this the best we can do is to replace the EBCM. If that doesn't work, you'll have to go back and replace the BPMV.
The procedure for removing the EBCM is very simple. The only special tool you need is a T-20 torx screw driver. I have a Craftsman tool set that has a 1/4" drive screwdriver with and adapter for many different size bit. Unfortunately, the adapter was to long to fit between the EBCM and water pump, so I purchased a set of Craftsman 5 pc. torx screwdriver set that worked fine. A flathead screwdriver may also be needed to pry apart the EBCM from the BPMV
1 - make sure the car is off.
2 - you will probably need to remove the airbridge to get to the EBCM.
3 - remove the wire harness by first removing the white plastic clip that locks it in place (I cut it off and replaced it with a zip-tie) , then lift gray handle and pull back on the wire harness . At this point, you will be able to see the second wire connection that is removed by pulling down .
4 - The service manual call for you the remove the 2 insulator nuts that hold the BPMV to the brackets and lift the EBCM/BPMV out of the bracket. I do not think this step is necessary because there is plenty of room while it is still in the bracket and you do not gain much additional clearance since the brake lines restrict the movement.
5 - Remove the 6 T-20 torx screws connecting the EBCM and BPMV - 1 on each corner and 2 on the sides .
6 - "Separate the EBCM from the BPMV by gently pulling apart until separated" - I should start laughing here, but it's not that funny. It's been my experience that anytime the instructions call for you to do something gently, nothing gentle is going to work. In this case, I had to use a flathead screw driver to brake the seal. Once it moved a little, the rest was easy. In addition to the rubber seal, each of the 12 holes have a peg in them from the BPMV. Don't go crazy, but be prepared to force them apart.
7 - At this point, you send it to ABS FIXER and all you've got to do is put it all back together (by the way, you can safely continue to drive your car without the EBCM, just remember that your electronic driving aids are no longer functioning so you should adjust your driving habits accordingly) When you get it back,push the repaired EBCM onto the BPMV.
8 - Replace the 6 T-20 torx screws
9 - reconnect the wire harness
10 - put the intake back on
An alternative to buying a new one is to have your original rebuilt.
For EBCM repair/replace
Call Brandon
877-648-7530 at ABS FIXER
or: www.absfixer.com
$150. plus UPS....warranted as long as You own it
