Brake problem, Code C0265

[Dennis S]

I haven't seen anything like this in the forum so forgive me if this has already been answered. I finally broke down and took my '01 Crew Cab 4.3L to the shop today because the ABS and Brake lights on the dash have been coming on. Between customers, the mechanic ,"Jim", was nice enough to help and he pulled Code C0265...EBCM Relay - Open. We have not yet located the EBCM relay...neither the Owner's Manual nor Haynes seems to identify it. (Jim was busy and I was in a hurry) The lights have been coming on intermittently for about three months. They don't blink, just stay lit. I haven't noticed what causes them to come on yet but I have noticed a few things. At first, I was able to restart the truck and reset the lights which of course doesn't work any longer. At lunch or on the drive home, the lights usually come on when I start the truck and will then stay on. Usually in the morning drive, the lights don't come on at all...occasionally they will when I hit a bump in the road though. I have not felt any change in brake "feel" or effectiveness during normal city driving/stopping. Haven;t done it in a while but I had noticed that during a stop on sand/gravel and the ABs kicked in, the lights came on.

A little history on this... Last year I noticed that if the ABS engaged or if I pushed firmly, the brake pedal would go all the way in so bled the brakes myself last year. Didn't solve the problem and the mechanic suspected a bad master cylinder which I swapped (rebuilt) but had no affect. I always suspected that there may still be air trapped in the lines so a couple months ago after the dash lights started their thing, I took the truck in to have the brakes 'pressure-bled'. That mechanic, "Gary", noticed that the rear discs showed over-heat marks (discolored and spider-web marks). I thought that was odd since all the pads and discs were changed in '05. So, I changed the rear brakes. Today Jim thought he noticed that the brakes seem to drag...I thought I had noticed that also 'cause the engine seemed to lack power in the 95°-plus heat but had chalked it up parasitic loss from the cooling fan. Also, Jim noticed that his code scanner showed the truck moving at 3MPH while parked in the shop.

There has been no identifiable pattern to the lights coming on except that they usually come on in the heat of day. Has anyone experinced anything similar? I would like to change the EBCM Relay, does anyone know were it's located? Any other ideas how to further diagnose my brake issues? I'll be lifting the truck as soon as I can to spin the wheels and see if they drag or free-wheel.

Denny

[T Man]

Another 4dr'er. Wahoo

As far as I know the ecbm relay is under the hood in the fuxe and relay center, but I will do some looking on mitchell tomorrow and see if i cant find anything different. As far as dragging rear brakes, try pulling the caliper slide pins out, throughly cleaning them with emry cloth, and using a wire brush and some brake clean to get the holes for them cleaned out as well. Make sure to lube them using a sillicone brake lube. If this doesnt cure the problem, it may be time to replace the calipers.

[Dennis S]

Had a little time so I put the rear axel on jacks and Trans in <N>. Didn't matter which wheel I turn, the other stays still but of course, the drive shaft spins. I can hear that the brake pads are dragging although, I suppose I could be hearing the e-brake shoes dragging. It didn't take a LOT of effort to spin a wheel but they definitely don't spin freely. Since everything from the wheel through the diff, transfer case and into the transmission is turning, I almost think that this might be normal....?????

Lifted each front wheel one at a time. They definitely take more effort to spin than the rear wheels. I didn't hear the brakes dragging though. Would this be typical since it's a 4X4?

I have changed the oil in both diffs about a year ago with Royal Purple.

While trying to spin the tires, I was just imagining how much gas mileage i might gain with free-spinning wheels if I do have a problem..... I'm getting about 12.5-13 MPG going 10 miles to work and back in city driving. I've got 3.42 gears and Goodyear Silent Armor LT235/75-15 around.

[Mikz86TA]

ECBM stands for Electronic Brake Control Module. It is the big part that the brake lines go into and back out of from the MasterCyl and to the Brakes. It is also the ABS motor all in one. The relay is under the hood at the Fuse/Relay center just inbetween the EBCM/ABS and AirIntake. Relays are big and square. The underside of the Fuse/Relay center cover has the ID and placement embossed into it of everything in the F/R center. Be sure to check the fuses first. The relay needs power to operate and the EBCM or ABS or Brake fuse will be the one for it. About the rest...try what T-Man said. Ironically most people and some shops dont actually do a thourough brake service. They miss good cleaning of reused hard parts, dont inspect the rotors for needed turning and/or dont lube moving parts

[Dennis S]

Mikez, thanks for the detailed explaination. I took a second look at the fuse relay center and verified what I had seen (or not seen) before. There is a 60A Fuse for ABS but I didn't see anything else for ABS or EBCM. The fuse is good. There are several fuses and relays installed for items that I don't believe are installed on my truck like Foglights. The Owner's Manual lists each fuse code but doesn't describe the relays in detail. I looked at the code for each relay under the cover but didn't see anything that remotely looked like it would be for ABS, EBCM, Brakes, etc.

Could it be possible that there is an EBCM relay disguised under a code that seems unrelated? Could the EBCM fuse be located somewhere else in the vehicle?

I did find a fuse in the driver side dash fuse block that checks good.
Last night and this morning when the lights were not lit, I found some loose gravel; The ABS system engaged and the lights stayed off. Tonight when coming home from work, I started the truck and the lights came on, restarted and the lights stayed off.
Really has me confused....:confused:

[Mikz86TA]

OK...I searched and found out some info. Apparently this is a common code on many '99-'04 GM Trucks abd SUVs. It is sometimes accompanied by C0201 and may include another code as well. There is only the 60A ABS fuse under the hood which is Ignition based and is power for a bothe the EBCM and ABS Motor which is why its such a high current draw circuit. There is a 10A fuse inside the truck in that fuse panel which is for the ECBM power. The ECBM is essentally a big relay which is why it is listed as that in the code scanner. Older ABS apparently used less sophisticated units like this Kelsey-Hayes module and just had simple relays/module. There is a possibility of 2 things happening. A bad ECBM. Or a bad, shorting ground for the ECBM. Remember a relay needs 2 things to function....power and ground. If its open when its suposed to be closed/engaged, then you have bad internal circuit or power/ground loss. If you have verified the underhood fuse 60A and the side-dash fuse 10A are not blown, then next check the ground. The ECBM/ABS module is under the hood behind the underhood fuse/relay center. You will see 1st 2 sort of large wires (one red and one black). Those are for the motor. On the back underside, you will see a harness coming from the ECBM. It has about 10 wires (brown,yellow,d.green,blk/white,yell/blk,l.blue,tan,purple,l.blue2,purple2). This will let you know you are on the right part. It uses the chassis to ground when its mounted to the bracket and also the large black motor wire ground should be good. Ground number is G110 and is grounded to the chassis near the widsheild washer pump or behind the left headlight. The one behind the headlight is down low on the backside of the radiator shroud. If you are still rockin the stock airbox, you might need to remove it. It is just to the insude of a splice pack ( a green ended connector attached to the shroud too). Hope this helps you find out the problem. You can use a multimeter on continuity to test the wire or module to a 'known' ground. Try messing with the ECBM harnesses while doing it, to find a intermittent miss. Try running a wire from the ECBM motor wire or ECBM housing case to a 'known' ground. Then road test as needed. Hope this helps =)

[millerrerik]

Have you found out what the code is and how to fix it? I went today to the shop and the EXACT same thing is happening with my 2001 GMC Yukon XL. Have not found anything on the internet to tell me what the code is. Any help would be great! Thanks.

[Dennis S]

Well, the code I got was: C0265...EBCM Relay - Open. In short, no I haven't found the cause yet. Mikz had the best explaination of what it could be. I haven't had a chance to chase the ground wire down yet...maybe this weekend. I have pulled the brake calipers off and cleaned/greased them. Since I had everything apart, I pulled the two front wheel-speed sensors. I wanted to check them for possible problems that would cause a 3mph reading while I was parked. Although I don't know what is normal, they looked fine. I haven't found the rear-wheel speed sensor but suspect that it is sticking out the top left side of my transfer case.

[Dennis S]

I pulled the airbox out today and found the Ground right where MikZ said it would be. It had a little corrosion so I cleaned that. I also found a small wire going to a screw on the firewall along with the ground strap from the hood. My multimeter is on the fritz so I wasn't able to verify that ground wire(s) ahve continuity; I"ll have to borrow a meter from work next week. I just don't like splicing into wires when it's not necessary. After cleaning the ground lugs the ABS and E-Brake lights came on a couple times but haven't for several restarts.

It is darned hard to troubleshoot something that only fails part of the time...

I've haven't seen a factory service manual. Would they have more information about how the ABS works or how the wires are routed? Wondering how much one might cost and if they were worth the money for general maintenance and troubleshooting weird problems like my brake issue......

[Mikz86TA]

GM service manual would be the most conclusive in details and diagrame. The one I got for my TA has been a lifesaver. Good to see you tracked down some stuff. Could still be the ABS module. Thats probably expensive and would suk to replace. Fill us in as you find out more info. THX

[Dennis S]

Well, I got out the multimeter this morning. I have good continuity through heavy guage black wire that runs from under the air box to the ABS Module. No amount of wiggling/pulling on the wire showed anything but a short. I did notice that I don't have a good ground on the short black wire that runs along the firewall from the top of hte ABS module to the lower ABS section. I imagine that this runs the ABS pump and wouldn't have continuity unless the ABS was actually engaged....I think.

It's looking more and more like I may have a bad ABS module. Does anyone have a ball-park cost for one of those?

[Quarterbore]

Through the power of Google I have found this thread and I am in the same boat. Our 2001 S-10 blazer 4x4 has the same CO265 Code and in other searches I found references to check the ground and fuses and they are all fine on our truck.

This module is an $850+ part through the dealer and I did confirm that without this thing working the brakes will work as standard non-ABS brakes so I declined to have the dealer do it at $930 w/ labor.

I have a few U-Pull salvage lots around and I plan to try to find one that way and save some money. I have seen reference to both 2WD and 4WD units but I have not found a parts list to tell me if there really is a difference. Then again, in my part of the country most S10 blazers are 4WD....

Our truck is just too old to justify nearly $1k IMHO.

[OrlandoXtreme]

having the same problem, junk yards want about $250 for a unit

[jharrison]

I never had a code come up, but the spongy brakes, and the intermittent ABS and E-Brake lights that come on and stay on are my symptoms. I went to Brake Check and they diagnosed the problem as the master cylinder and here I am 4 new masters later with the same problem. On a loose gravel road the ABS does exactly what it should. Does the code come up with a typical OBD II code reader, or is something special required?

[GMAC01]

All,

Just following up on C0265. My ABS and Brake lights both come on at the same time when I start my 2000 Chevy S-10 4WD pickup after it's been sitting several hours in the hot sun (90 degrees plus). I took off ground 110, cleaned the surfaces and then reapplied G110. No luck. It appears the problem is a relay inside the EBCM.

An E-Bay webpage (see item# 280255354999) states that the relay in the EBCM may stop functioning properly due to the load placed upon it and that they will replace the relay with a better relay for $150.00 plus $7.00 in shipping costs. I wonder if someone could simply unsolder the relay, clean it and then resolder it into place themselves?

If anyone is interested, I may pull out the unit and do a little experimentation of my own...

Shawn
Colorado

[madmax]

3mph is the lowest chevy 4 wheel abs will read on several vehicles including s-series and astros.