99 EBCM Conversion to 01-04 EBCM -- Success!
 

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! :thumbs:
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.

Many thanks to MRR23 in this thread who did much of the legwork on how to repin the harness in my 99:https://www.corvetteforum.com/forums...-97-00-c5.html

Parts Needed:

• 2001-2004 C5 EBCM and BPMV [These can be sourced from one of the C5 recyclers, the auction site, or purchased new.]
• 2001-2004 C5 ABS Bracket [Source: auction site]
• 2001-2004 C5 ABS wiring harness [source: auction site]
• 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:

https://cimg6.ibsrv.net/gimg/www.cor...09a8b931d9.jpg


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:

https://cimg5.ibsrv.net/gimg/www.cor...265d169e43.jpg

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):

https://cimg9.ibsrv.net/gimg/www.cor...ca315361cf.jpg



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.

https://cimg2.ibsrv.net/gimg/www.cor...c508975699.jpg


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:


https://cimg4.ibsrv.net/gimg/www.cor...0a99672309.jpg

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.


https://cimg3.ibsrv.net/gimg/www.cor...81761d8d20.jpg



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! :willy:

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.

Nice wright up. Can't wait to see the pics. Alot of PPL will like this.

Way to go. :thumbs:

I knew it would work if someone was wiling to ignore the scare tactics posted about the whole electrical system being different and instead just dive in and do it. My car works so I have no motivation to take on another project.

Best part is you can sell your old EBTCM for big $$, probably enough to pay for most if not all of the swap parts.

Just to note. I'm pretty sure you could have taken the connectors apart and moved the small signal pins from the old connector to the new connector. They look just like the PCM connectors and those are easy to swap pins in.

Congrats. Glad i was able to help out in this endeavour. I will be reading this over again. Look forward to pictures.

Thanks for the kind words. Your earlier posts encouraged me that it was possible. The hardest part was actually making the decision to jump in and get it done.

I initially tried to take the existing ABS connector apart and move the pins over to the new connector. Unfortunately, GM changed the size of the pins slightly and the 99 pins wouldn't fit into the late model ABS connector. The job would have gone much easier if it would have worked.

I have 2 working EBCMs for my 99 that I plan to sell to offset the cost above.
Estimated cost:

2001-2004 C5 EBCM & BPMV (Ebay): $120
2001-2004 C5 SWPS: $ 75
2001-2004 C5 front hard brake lines: $100
2001-2004 C5 brakes lines from master to bpmv: $35
2001-2004 C5 ABS Pump Bracket: $25
2001-2004 C5 ABS pressure sensor & wiring: $40
Late C5 ABS wiring harnesses: $85 (I bought 2 to experiment with)
The above totals approximately $480.

Labor is difficult to quantify. I spent many hours making sure the wiring worked, changing out the brake lines, etc. If I had to guess - I would say I spent close to 80-100 hours on the project. Hopefully, the next person to go through this can get it done quicker. The hardest part was sourcing all the parts and making the wiring changes.

I spent another $100 or so on tools (bubble flare set and tubing bender), along with brake lines, fittings and heat shrink connectors.

Most excellent!!!! I knew this had to be doable! Gives some more life to the mid year 98 through 00 cars. Well done sir!!!

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.

Wow, great job sourcing parts too. That was way less than I expected. I was expecting you to easily be over $1k in parts. You'll pay for your parts and for the beer you drank too!

That sucks that the pin sizes in the connectors were different. Leave it to GM to change them just enough they won't swap instead of using the same parts.


That's what Steve Doten posted once or twice. He posted that he'd do the swap but had yet to find anyone willing to spend $3k on a $10k car.

Very informative, I love these kind of threads! :cheers:

Where I'm from, ABS failure results in the car not being legally allowed to drive on the road.

These results are such a relief for me, an owner of a '99. I would happily spend good money for a kit of some kind for this conversion. I love my'99 and plan on running high miles into it, so would love the piece of mind of being able to keep it running properly.

This expense is easily justifiable if your car has to pass inspection, the ABS/TCS is degraded to the point of performance limitations, or your car is one of those things that if it's broke, it NEEDS to be fixed.

I know these cars are a dime a dozen, but have the 98-00's with the ABS/TCS issues really become throwaways once the problems rear their heads, or would it be worth it tossing the money into it knowing that you just took care of the lions share of the nightmare problems for these specific years?

Just my personal thought, $2K to $3K might be pushing it on the price. The hardest part of the work I can see would be dropping in the new front lines and fabbing up the rears to work because you're in such tight confines. Repinning the SWPS harness isn't that big a deal, and cut/splice matching of the new EBCM plug is pretty simple. The major hard parts, while tight confines, are drop in's essentially. Honestly if you brought someone all the parts, I would be willing to think $1K would cover all the labor. I know if I was doing it for someone I'd feel guilty charging them that much for it, but I work with brake lines a lot and am very comfortable with that part too.

I would not have a problem paying $1K in labor plus $500 in parts to have this done to my car. If my EBCM goes out now and I buy a used replacement, I will be paying nearly as much. This way if the EBCM goes out, just have it rebuilt. Seems way worth it to me. The only issue would be finding someone that would be willing to do it.
I could see a huge market for this.

Im amazed that GM didn't do a retrofit kit for this. BUT,,,,, I guess the Corporate LEGAL PEOPLE put the LID on that.

Some aftermarket company needs to jump on the opportunity..

Excellent work! :cheers:

Bill

80-100 hours included how much research time though? If you had the pinouts in front of you, and all the parts on hand, this conversion should EASILY be doable in under 20 hours. The first time ALWAYS will have drastically extended time involved because it's the first time. The leg work was done there.

Just off the top of my head.....R&R the old ABS Valve/EBCM for the New One including bracket.....let's say 2 hours. SWPS swap......never pulled a C5 steering wheel....1.5 in and out maybe? So 3.5 hours for the hard parts. That's 16.5 hours left over to fab and/or drop in new brake lines and do a cut/splice on the EBCM connector and repin the SWPS, then bleed and verify operation. That's quite a bit of time. Mind you this is all thinking "professional mechanic" times and not garage mechanic times, but if you're going to DIY, the cost/time is relatively moot at that point.

Another possibly benefit to this.....I have a friend who's working on a 97 that was sitting for a couple of years. MAJOR issues. I showed him this and he's going to look into the feasibility of retrofitting the 01-04 and doing a front ABS mounted conversion on the 97. We've discussed the larger job it would be in terms of relocating the wiring and a complete brake line redo on the car, but he seems undaunted.

My 80-100 hour estimate included a LOT of research time. I'd guess over half. I also spent another 8-10 hours sourcing the right tools and supplies (fitting sizes, etc.). The labor cost would likely be substantial. I would have never attempted this without knowing I was going to do all the labor myself.

I was asked for the ABS pinout used in the conversion. I used the pinout in this post (thanks again to MRR23): https://www.corvetteforum.com/forums...post1590241862

great job

Fantastic work!.......Many thanks for your hard work and posting your results.:cheers:

Moderators....Can this and the linked threads be made a sticky?....Thanks

:cheers: :cool: