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ABS SYSTEM QUESTION C1243


tdcrash63

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ABS is coming on as soon as car is started. it is logging a C1243 no other codes present. Checked power to unit. Power through fuses in fuse box in engine compartment, large 30 and 40 amp fuses. Disconnected plug from EBTCM have battery voltage on pins E red 342 wire and red white 442. Power goes away on these wires if fuses are pulled so I take it they are the power wires to the ebtcm and bpmv. Have 3 ohms resistance from the ground on the motor case to the ground on the left side shock tower. Have 3 omhs resistance from the shock tower ground to the battery negative. How do I determine which has failed the engine brake traction control module or the brake pressure modulating valve. Am I missing something such as a possible bad pressure sensor somewhere. My manual indicates failure of one of these 2 components Any help

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....Have 3 ohms resistance from the ground on the motor case to the ground on the left side shock tower. Have 3 omhs resistance from the shock tower ground to the battery negative.

Do you have faith in your Ohmmeter?

That is far too much resistance in the chassis ground circuit for the pump motor.

If it was my car, I would take all those chassis ground conections apart, wire brush all the terminals and chassis attach points and try again.

Or, you could fabricate a redundant ground stap connected between the pump motor ground terminal and a known good chassis ground return point as a test.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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....Have 3 ohms resistance from the ground on the motor case to the ground on the left side shock tower. Have 3 omhs resistance from the shock tower ground to the battery negative.

Do you have faith in your Ohmmeter?

That is far too much resistance in the chassis ground circuit for the pump motor.

If it was my car, I would take all those chassis ground conections apart, wire brush all the terminals and chassis attach points and try again.

Or, you could fabricate a redundant ground stap connected between the pump motor ground terminal and a known good chassis ground return point as a test.

I will run a redundent ground from the motor to the negetive battery terminal, The meter is digital snap on middle of the road so it should be fairly acurate. Any other advice
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I will run a redundent ground....Any other advice

Not before you report results of the redundant ground test.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I will run a redundent ground....Any other advice

Not before you report results of the redundant ground test.

Checked ohm meter and leads again. Leads had about a ohm of resistance zeroed meter and retested 2 ohms. Disconnected wire from motor. Disconnected at pigtail 6 inches up. Motor stud was not real tight as it turned 1/3 of a turn when wire was loosend. Tighten motor stud. Clean eyelet end and connector as best I could. Both looked ok no green color ect. Nevada car very little moisture. Reconnected. Retested. zero ohms resistance now. Turned on ignition and started car 5 times. ABS and stability lights are not on. I will leave the lower splash gaurd off and let you know if this returns. This started as a intermittiant problem until yesterday as well as this morning it was on every time the car was started. Thanks for the help will repost in a few days or if problem surfaces again.

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Well done. I would also use the ALL CLEAR CODES option in the on-board code reader.

Not all oxidation is visible to the naked eye. I associate obvious green corrosion with battery acid or acid vapors and limited to cables in close proximity to the battery.

Your Ohmmeter readings was a big red flag for me.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Up date on the 1243 code. Monday good, Tuesday good in the am apon leaving work. Started up car, active 1243 code ck abs and stability control on no other codes. Shut car off and restarted 2 more times. Code was gone on the 3rd try. Drove it home. Ran a ground wire from the Motor ground stud to ground terminal on the fender. Then ran a tempory wire from there through the passanger side door and directly to the battery. Cleared codes and tried it 20 times. Code logged once. Tapped lightly on the motor and tried several more times, no problems. Drove to work. Wed ok Thur logged in the am restarted car and code was gone. Same thing on Friday. I also noticed that if I stick the key in the ignition and crank the engine right away I am more likely to log this code than if I turn the ignition on and wait 3 to 5 seconds to start the car. Very rarly log this code doing it thst way. I would seem as though the motor is dragging just a little? any ideas or other checks I can do to remidy this problem

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Up on your first post, you said you saw appropriate Voltages on the EBTCM connector pins. But you did not mention applying contact cleaner or exercising the connector pins to scrub corrosion from the contacts. Just a thought.

I'm convinced you are on the path to a solution.

Thanks for the follow-up.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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  • 3 months later...

Been living with the intermitant 1243 code ABS light comes on traction control and stability disable. Got my hands on a factory service manual. Followed the diagnostic flow chart. Results pointed to the ABS pump it seems as if the module checks out and the supply and ground cucuits check out that you replace this componant No definite test result that was out of spec or obvious problem. Ordered a pump from a salvage yard. It came with the module. Removed the old pump and bench tested it by removing the module and putting 12 v to pin E of the module and ground to the case stud. Pump would run for 1 to 2 seconds then begin to slow down and draw a lot of amps. So that would explain why the code was very infrequent. I rarly used the system in my normal driving. The short run time was suffecent for startup usually. Bench tested the used one the same way. No problems pump moter would spin freely for a 60 seconds. Installed pump, module. Connected all wires. Bled the brakes. Road tested ok. Tested system out in a parking lot with sand in various spots. traction control and antilock funtions work now as they should. Also ohmed out the old motor and the new motor while it was on the bench no noticable differences. I am going to open up the old motor and see if it is possible to repair it. The motor says bosch on the back looks like a blower motor

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