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Theres a lot of cars out there with no ABS and Traction Control, I'm like several here I get the message every time I start the car and have to hit the Reset, its the only issue I have ever had in 20 years. Drives great.
Theres a lot of cars out there with no ABS and Traction Control, I'm like several here I get the message every time I start the car and have to hit the Reset, its the only issue I have ever had in 20 years. Drives great.
Yea. I don't mind hitting the reset. It doesn't bother me.
Awesome your car has been great.
Mine is running great.
I do need to figure out how to disable power to the visors.
I haven't looked for a thread on that.
I want to just shut of the lights in the visor mirrors.
This is a fantastic write up. I have been driving my 99 Convertible for about 5 years without ABS. Last year I had a run in with a huge buck deer. Slid the front tires, hit the deer in the belly with the nose of my Vette. With the top down, I watch him fly up and over onto the highway behind me. No major damage, flat spotted tires, broken passenger side headlight cover, small cracks in bumper over and leading edge of the hood. If I had working ABS it likely would not have hit the deer at all.
]This is a fantastic write up. I have been driving my 99 Convertible for about 5 years without ABS. Last year I had a run in with a huge buck deer. Slid the front tires, hit the deer in the belly with the nose of my Vette. With the top down, I watch him fly up and over onto the highway behind me. No major damage, flat spotted tires, broken passenger side headlight cover, small cracks in bumper over and leading edge of the hood. If I had working ABS it likely would not have hit the deer at all.
My next project will be this ABS upgrade.[/QUOTE]
That's crazy the deer would go flying like that and the Vette doesn't have much damage.
I hope to avoid hitting deer, or anything.
Hello I'm new to this site but I'm so thankful for your help with my 1999 EBCM worries. I'm not very mechanical so I'm hoping that you or someone you know can upgrade my EBCM. Let me know if that's possible. And again thanks for your consideration. David
Wiring:
The EBCM connectors are shaped differently between the 99 and late model C5s. I bought a used EBCM connector from a 2001-2004 C5 and spliced that into the existing harness in my 99. I staggered the cuts and spliced all wiring using heat shrink butt connectors. The pin out mentioned above was used as a reference on how to wire the new connector.
In process picture:
@Caddy2006 I see that this picture says it's "in process". How many total connections are there that have to be soldered? I'm assuming that it's the 6 wires labeled with letters and all of the wires in the 32 pin harness as well?
As the owner of a 1999 FRC with active handling, I have been worried about the potential future failure of the EBCM and the prospect of dealing with either inoperable AH/ABS or rolling the dice with a used EBCM of unknown origin. In short - the 1999 to 2000 AH EBCM CAN be converted to the 2001 - 2004 EBCM!
I've been driving my FRC the last 3 months to make sure I didn't have any issues. All ABS/AH functions work seamlessly and no PCM change was required. I'll post pictures later this evening when I'm able - but I wanted to summarize the process and parts required.
Background:
Unlike others, my EBCM didn't fail. I did have issues with the BPMV in 2012 and replaced it with a new unit. In March 2015 I started to have issues with the BPMV again (extremely soft pedal that wouldn't go away with any amount of bleeding). I put the car on blocks in April 2015 and vowed that I wouldn't take it down until the brake problems were fully fixed. After bleeding gallons of brake fluid with Automated ABS bleeds, pressure bleeds, gravity bleeds and manual bleeds - I gave up on the existing EBCM/BPMV and decided to convert the system over to the late model C5 system. I had read numerous threads about the potential of converting over - but nothing definitive. I studied the wiring diagrams in the 99 and 2002 service manuals and finally realized it was doable.
2001-2004 C5 hard brake lines from master cylinder to BPMV [source: auction site]
2001-2004 C5 hard brake lines from BPMV to both front wheels [source: auction site]
2001-2004 C5 ABS Pressure Sensor and pigtail [source: auction site]
2001-2004 C5 Steering Wheel Position Sensor [source: new from GM]
Tools / Supplies Needed:
Tech 2 [This one isn't really optional. Used to run automated bleeds and function tests. I used one of the Chinese clones and had no issues.]
Brake lines and fittings [To custom bend and splice into existing hard line]
ISO Bubble Flare Tool [required to match the fittings on the C5 BPMV
Brake line bending pliers [To form new hard line from BPMV]
Heat shrink butt connectors [To splice in new EBCM connector]
Pressure brake bleeder [used during automated bleeding]
Removal:
This is pretty straight-forward. Remove the existing hard lines from the master cylinder to the BPMV and remove the BPMV/EBCM from the vehicle. Also remove the BPMV bracket and hard brake lines from the BPMV to the front 2 wheels.
Wiring:
The EBCM connectors are shaped differently between the 99 and late model C5s. I bought a used EBCM connector from a 2001-2004 C5 and spliced that into the existing harness in my 99. I staggered the cuts and spliced all wiring using heat shrink butt connectors. The pin out mentioned above was used as a reference on how to wire the new connector.
In process picture:
The late model steering wheel position sensor (SWPS) installs the same as the existing SWPS - and uses the same physical connector. It just has to be re-pinned. I will upload pics of how to repin this harness.
SWPS connector:
Diagram on how to repin the SWPS harness (the light blue analog signal wire from the 99 is unused on the late model SWPS - I just wrapped it in electrical tape and made sure it was out of the way. The other end of the same wire is unused at the late model EBCM):
The Brake Pressure sensor on the BPMV uses the wires from the proportioning valve on the 99. The late model C5 doesn't use this valve and the wires from this switch are used to plug into the Brake pressure sensor. I used an extra weatherpak connector from a used late model C5 wiring harness.
The black sensor on the end of the proportioning valve below is the wiring used to go to the ABS pressure sensor on the late model BPMV.
Plumbing:
I used the 2 front hard brake lines from a late model C5 (BPMV to front wheels) to keep the install as clean as possible. Install these prior to installing the late model C5 BPMV bracket to give a little extra room.
One of the rear hard brake lines was bent slightly so that it could be reused with the late model BPMV. The other rear brake line was cut and spliced with a custom bent section of brake line to the BPMV. Be sure to use an ISO bubble flare tool on all connections. I will post pictures where I spliced into the existing line.
This picture was taken through the drivers side wheel well and shows the location of the splice:
This shows the line I custom bent. It's the line on the right - I got in a hurry and failed to take a picture before getting the radiator hose back on. I tried to follow the stock line routing.
Testing:
Once everything above is installed, the new unit can be tested and bled with the Tech 2. Have plenty of brake fluid on hand. Throughout this ordeal, I went through over 8 gallons of brake fluid!
Overall Thoughts:
The ABS/AH functions the same as it did prior to the install. No codes or strange message on the DIC. This install is very doable - either for an average DIYer like myself or a shop.
I will post pictures later this evening as well as answer any questions.
Hello Caddy 2006.
I am a new owner of a 98 C5. with only 27,000 miles. Well I got a great deal on it but the EBCM is out on it. The dreaded C1255 code. So I have been researching on how to replace it and was also wondering if you could install the later module. So my question is, when wiring the 01 plug in is it Color to color when splicing the wires or is it pin for pin example F pin to F pin? I am really thinking this is the best way to go. 10 years ago it was a lot cheaper for the parts it looks like. In 2024 I have estimated that it would cost about $2000 just for the parts to do the swap.
Someone really needs to make a YouTube video on this conversion. I will donate my car (LOL), for the cause but I get to help and/or do the work.
Hello Caddy 2006.
I am a new owner of a 98 C5. with only 27,000 miles. Well I got a great deal on it but the EBCM is out on it. The dreaded C1255 code. So I have been researching on how to replace it and was also wondering if you could install the later module. So my question is, when wiring the 01 plug in is it Color to color when splicing the wires or is it pin for pin example F pin to F pin? I am really thinking this is the best way to go. 10 years ago it was a lot cheaper for the parts it looks like. In 2024 I have estimated that it would cost about $2000 just for the parts to do the swap.
Someone really needs to make a YouTube video on this conversion. I will donate my car (LOL), for the cause but I get to help and/or do the work.
Thank you for any assistance.
I'm testing the limits of my memory - but I do know that I spent many hours studying the wiring diagram for the late model EBCM and comparing to the early model. I mapped out how the EBCM harness needed to be rewired so that the later model EBCM was receiving the correct signals from the early model chassis wiring. I know it wasn't 100% pin to pin - but I also wouldn't trust color to color. It wasn't difficult - just tedious.
I'm testing the limits of my memory - but I do know that I spent many hours studying the wiring diagram for the late model EBCM and comparing to the early model. I mapped out how the EBCM harness needed to be rewired so that the later model EBCM was receiving the correct signals from the early model chassis wiring. I know it wasn't 100% pin to pin - but I also wouldn't trust color to color. It wasn't difficult - just tedious.
Best of luck!
I've got my car in the garage on jack stands and I'm trying to work up the nerve to tackle this. I'll be honest, electrical isn't my thing and I'm a little intimidated by this.
It looks like @mrr23 hasn't been on here in a while. He mentioned diagrams in this post but I'm not seeing them. Any chance you might still have a copy of those diagrams you could share?
@lionelhutz I saw that you had mentioned studying the wiring between the early cars and the later ones. Any chance you might have the splicing diagram.
So, after digging through some old posts, I found the following diagrams. I'm now in the process of trying to figure out the splicing for the early harness to the late plug. 2002 EBCM diagram 1999 EBCM diagram
Alright, here's my attempt at a splicing chart for this. I've never attempted anything like this before, but this makes sense to me. I'm happy to accept any feedback / criticism before I attack my car with wire cutters.
As the owner of a 1999 FRC with active handling, I have been worried about the potential future failure of the EBCM and the prospect of dealing with either inoperable AH/ABS or rolling the dice with a used EBCM of unknown origin. In short - the 1999 to 2000 AH EBCM CAN be converted to the 2001 - 2004 EBCM!
I've been driving my FRC the last 3 months to make sure I didn't have any issues. All ABS/AH functions work seamlessly and no PCM change was required. I'll post pictures later this evening when I'm able - but I wanted to summarize the process and parts required.
Background:
Unlike others, my EBCM didn't fail. I did have issues with the BPMV in 2012 and replaced it with a new unit. In March 2015 I started to have issues with the BPMV again (extremely soft pedal that wouldn't go away with any amount of bleeding). I put the car on blocks in April 2015 and vowed that I wouldn't take it down until the brake problems were fully fixed. After bleeding gallons of brake fluid with Automated ABS bleeds, pressure bleeds, gravity bleeds and manual bleeds - I gave up on the existing EBCM/BPMV and decided to convert the system over to the late model C5 system. I had read numerous threads about the potential of converting over - but nothing definitive. I studied the wiring diagrams in the 99 and 2002 service manuals and finally realized it was doable.
2001-2004 C5 hard brake lines from master cylinder to BPMV [source: auction site]
2001-2004 C5 hard brake lines from BPMV to both front wheels [source: auction site]
2001-2004 C5 ABS Pressure Sensor and pigtail [source: auction site]
2001-2004 C5 Steering Wheel Position Sensor [source: new from GM]
Tools / Supplies Needed:
Tech 2 [This one isn't really optional. Used to run automated bleeds and function tests. I used one of the Chinese clones and had no issues.]
Brake lines and fittings [To custom bend and splice into existing hard line]
ISO Bubble Flare Tool [required to match the fittings on the C5 BPMV
Brake line bending pliers [To form new hard line from BPMV]
Heat shrink butt connectors [To splice in new EBCM connector]
Pressure brake bleeder [used during automated bleeding]
Removal:
This is pretty straight-forward. Remove the existing hard lines from the master cylinder to the BPMV and remove the BPMV/EBCM from the vehicle. Also remove the BPMV bracket and hard brake lines from the BPMV to the front 2 wheels.
Wiring:
The EBCM connectors are shaped differently between the 99 and late model C5s. I bought a used EBCM connector from a 2001-2004 C5 and spliced that into the existing harness in my 99. I staggered the cuts and spliced all wiring using heat shrink butt connectors. The pin out mentioned above was used as a reference on how to wire the new connector.
In process picture:
The late model steering wheel position sensor (SWPS) installs the same as the existing SWPS - and uses the same physical connector. It just has to be re-pinned. I will upload pics of how to repin this harness.
SWPS connector:
Diagram on how to repin the SWPS harness (the light blue analog signal wire from the 99 is unused on the late model SWPS - I just wrapped it in electrical tape and made sure it was out of the way. The other end of the same wire is unused at the late model EBCM):
The Brake Pressure sensor on the BPMV uses the wires from the proportioning valve on the 99. The late model C5 doesn't use this valve and the wires from this switch are used to plug into the Brake pressure sensor. I used an extra weatherpak connector from a used late model C5 wiring harness.
The black sensor on the end of the proportioning valve below is the wiring used to go to the ABS pressure sensor on the late model BPMV.
Plumbing:
I used the 2 front hard brake lines from a late model C5 (BPMV to front wheels) to keep the install as clean as possible. Install these prior to installing the late model C5 BPMV bracket to give a little extra room.
One of the rear hard brake lines was bent slightly so that it could be reused with the late model BPMV. The other rear brake line was cut and spliced with a custom bent section of brake line to the BPMV. Be sure to use an ISO bubble flare tool on all connections. I will post pictures where I spliced into the existing line.
This picture was taken through the drivers side wheel well and shows the location of the splice:
This shows the line I custom bent. It's the line on the right - I got in a hurry and failed to take a picture before getting the radiator hose back on. I tried to follow the stock line routing.
Testing:
Once everything above is installed, the new unit can be tested and bled with the Tech 2. Have plenty of brake fluid on hand. Throughout this ordeal, I went through over 8 gallons of brake fluid!
Overall Thoughts:
The ABS/AH functions the same as it did prior to the install. No codes or strange message on the DIC. This install is very doable - either for an average DIYer like myself or a shop.
I will post pictures later this evening as well as answer any questions.
Hello I'm hoping that you receive my message. I've never been on or attempted to get in touch with anyone on here but I'm truly hoping that I can. I'm so excited and impressed with your EBCM conversion. I've got a 99 Corvette C5 convertible and I love it and I don't want to be worrying about not being able to get it repaired properly. I'm not the do it yourself kind of guy. LOL 😂 I'm 70 years old and I'm hoping that you would be interested in rebuilding mine. Please feel free to contact me anytime at my Gmail of vetset5863@gmail.com. I don't often see my Gmail messages because I get so many telemarketers. I hope to hear from you soon. Thank you Dave Lythjohan
Last edited by Vetteman Jack; Jun 14, 2025 at 10:19 PM.
Reason: Removed phone contact number.
Thank you for the info. Have 1998 Coupe with 35,000 miles. Solid and Smoke tops. Always garaged, no driving in rain. So
some day, may have to take on this project. Thank you for work and info.
Your a brave and obviously talented car guy. I also own a 99 frc. Any idea how much you will want for one of those good 99 ecbm,s? Mine is still working but would like to have a known good one as spare. Mine is just starting to act up, is shows abs, TC fail, i turn off car , then restart it and it clears, but doesn’t make me feel like its going to last. Again im impressed! Jeff99. You can email a price at my13camaros@ yahoo.com when you’re set on a price.
Sounds like someone needs to market a DIY kit with all the parts and instructions.
Owners often spend thousands on hoods and body kits so why not this.
Yea, I see guys with maybe over $50K in performance mods and then the EBCM goes bad. If they are unable to fix it they may end up with, I have seen referred to as a "C5 door stop"
I have seen the problem talked about here and there but never knew it was such a big deal. I'm not a guy that really knows how to work on cars. I would get about as far as opening the hood and lost after that.
It only makes sense that some company will start making them for the early C5's. What's going to happen?
There will be hundreds of C5s piled up in the bone yard because they need some seemingly little part.
When I started reading about it I felt like “I better get rid of mine while I still can”
Get rid of my baby 98 with 21K on the clock that I have treated like a family member.
It would make me feel horrible, I wanted a C5 since I first saw one in 97.
But I realize it’s a 27 year old car so there may be a few bumps along the way. Now I think, it will
all turn out OK, hopefully before I die of old age.
I have had my 2000 now for about five years, and lived with the shadow of everybody worried about this. I know the minute that I post this it will go bad, but it has not. I figure driving it and cycling it on and off every once in a while is good for it. And if it goes bad? Well then you have a 1967 tech Corvette. Enjoy everybody!
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