FAQ: Anti-Lock Brakes and/or Traction Control Light/Lamp On

Last edited by stydel311 on Sat Feb 15, 2020 10:59 am; edited 1 time in total

Is it normal to have the abs pump run when first driving?

Last edited by stydel311 on Sat Feb 15, 2020 11:00 am; edited 1 time in total

stydel311 wrote:

stydel311 wrote:: About a month ago I was driving through town and the abs light came on, so now both the abs light and traction off lights are on (abs definitely doesn't work anymore). I pulled the abs light since I didn't have time to work on it. I'll get it scanned tomorrow but I'm wondering if anyone has any guesses as to what caused the abs to come on now. The original code was C1274 like stated earlier. Just to double check, is the EBTCM the computer mounted on the side of the strut tower on the drivers side?

Moving this from my other topic into this one. I got codes scanned an in addition to C1274 PMV Pressure Switch Circuit, now it pulls C1215 Suspect Valve Malfunction, C1256 Left Rear Outlet Valve Circuit, and C1237 Left Rear Wheel Speed is 0. I will go check the wiring to the left wheel sensor, are the other 3 codes indicators of a bad EBTCM?

Perhaps you could fix the wheel sensor and/or its wiring, clear all the codes, then see.

Also and hopefully it is not too late - change/flush the brake fluid. When it's brown it is moisture laden and the ABS does not like that. It should be no darker than clover honey (IMHO). You can use a synthetic fluid (may be sold as DOT 3, DOT 3/4 or DOT 4) to slow down the darkening. The brakes will be firmer with a DOT 4 fluid in. Crappy fluid will mess up the ABS/Trac system.

I took the wheel off this afternoon, hooked up the volt meter and got up to 4 millivolts when spinning the wheel. So, after assuming that the sensor in the hub is working, I followed the wire for it up to where it looms together with the wiring for the other side and goes into the connector clipped to the metal plates by the 2 other connectors. I couldn't get both hands under the car to get the pin out of the top and take the connector apart to look at the terminals. The wires coming out of these connectors loom together and go up through the floor to under the back seat, but after that they go into a loom of about 50 wires. I did find that the ground under the back seat on the drivers side was nasty so I fixed that. Currently still have the battery disconnected to make sure everything is reset. I would like to get that connector that's clipped to the metal plate apart to see if there is a break in the wiring between the sensor and that connector, otherwise the break would be between there and (I'm assuming the sensors are hooked up to the EBTCM) the EBTCM.

Last edited by stydel311 on Sat Feb 15, 2020 11:02 am; edited 1 time in total

Wiring from sensor reading 0mph has continuity all the way up to the connector on the EBTCM, wiring is good.

stydel311 wrote:: Wiring from sensor reading 0mph has continuity all the way up to the connector on the EBTCM, also has same resistance readings as the other side. Is it possible that there is something internally wrong with the EBTCM?

Yep.

Abaddon please weigh in - but IIRC the FSM says swap in a known good EBTCM to test at this point. I do not know if the EBTCM can be opened and repaired in the field. I have heard of rebild services such as this: http://www.ebay.com/itm/ABS-EBCM-COMPUTER-MODULE-REPAIR-KELSEY-HAYES-325-KH-325-BUICK-RAINIER-04-05-/282050213985?fits=Make%3ABuick&hash=item41ab80b861:g:8oMAAOSw6btXR2X9&vxp=mtr - but I have not had to use their (or any other) service so I can not say really.

Albertj

stydel311 wrote:: Wiring from sensor reading 0mph has continuity all the way up to the connector on the EBTCM, also has same resistance readings as the other side. Is it possible that there is something internally wrong with the EBTCM?

Did you ever figure out what the problem was? I have the same problem

Last edited by stydel311 on Sat Feb 15, 2020 11:03 am; edited 1 time in total

chitown_riv98 wrote:

stydel311 wrote:: Wiring from sensor reading 0mph has continuity all the way up to the connector on the EBTCM, also has same resistance readings as the other side. Is it possible that there is something internally wrong with the EBTCM?

Did you ever figure out what the problem was? I have the same problem

Speed sensor was bad.

stydel311 wrote:

chitown_riv98 wrote:

stydel311 wrote:: Wiring from sensor reading 0mph has continuity all the way up to the connector on the EBTCM, also has same resistance readings as the other side. Is it possible that there is something internally wrong with the EBTCM?

That's too bad, I've been trying to get the light to shut off with our success my self and was getting tempted to replace the EBTCM

Did you ever figure out what the problem was? I have the same problem

I swapped in a different ebtcm from eBay yesterday that was supposedly working, I was thinking there was something wrong on the circuit board of the original ebtcm so that it wasn't getting a connection internally to the pin on the connector for the rear sensor. Both lights are still on however but I haven't had a chance to get it scanned to see if it's the same codes, so it could be getting sensor signal but the light is on for some other reason. I did open up the original one (it's a pain, it's all sealed together) and reflowed all of the solder joints but it made no difference.

I watched the following, and wondered if your test was really telling you what you think it was telling you:

https://www.youtube.com/watch?v=qap4m_FR2J0

https://www.youtube.com/watch?v=H0HrG7sujvA

https://www.youtube.com/watch?v=ujc6pjftZ_w

I don't know what voltage the brake computer is expecting to see, and I don't know if the wheel sensors are magnetic or Hall Effect. I don't know if you ran your test key-on or -off nor do I know if the test was with sensor in circuit or disconnected. So - I'm sorry but I can't help you more with this, don't have the data.

Albertj

Don't measure the mV of the WSS. Instead, measure the resistance of the sensor itself. It should be somewhere between 850 and 1350 Ohms. Any higher or lower, the WSS is bad.

BTW, the mV reading for a functioning WSS is 100mV.

Proper resistance of a length of wire is .4 Ohms, give or take +/- .1 for temperature.

Abaddon wrote:: Don't measure the mV of the WSS. Instead, measure the resistance of the sensor itself. It should be somewhere between 850 and 1350 Ohms. Any higher or lower, the WSS is bad.

BTW, the mV reading for a functioning WSS is 100mV.

Proper resistance of a length of wire is .4 Ohms, give or take +/- .1 for temperature.

Well, if the WSS is sending 4 mV when it's supposed to send 100mV...

albertj wrote:: Well, if the WSS is sending 4 mV when it's supposed to send 100mV...

Correct. However, I'm willing to bet that the resistance is way off as well. I'm yet to see a WSS with the proper resistance reading and a wrong mV reading. Just easier to go right to Ohms instead of spinning the wheel.

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