93 six speed abs/asr problem

[forrest]

HI all the other day happily driving down the road out of no ware my SERVICE ABS & SERVICE ASR lights come on. parked the car figuring a momentary problem (NOPE ) as soon as I start moving ABS pump starts running (no ABS active light showing) touch the brakes, ABS ACTIVE light comes on and car feels like your stopping on ice. As expected the car calls NO JOY and shuts down the systems.

Got back home raised car unplugged wheel sensors gave them a spin they all seem to make give or take the same voltage as there mates both front both rears. I jumped the A to G and got the following codes

SYSTEM 1 CODE C-12
SYSTEM 4 CODE H-68 this one doesn't shock me my A/C system is a mess but works. from what I have read this is a A/C relay problem
SYSTEM 9 CODE H-31
SYSTEM 9 CODE H-31

opened up the FSM ran the trouble flow chart car passed all test in flow chart all the way down to plug in Tech 1

I do plan to clear all code later today.

Input would be Appreciated these parts are not cheap

 

[ecss]

HI all the other day happily driving down the road out of no ware my SERVICE ABS & SERVICE ASR lights come on. parked the car figuring a momentary problem (NOPE ) as soon as I start moving ABS pump starts running (no ABS active light showing) touch the brakes, ABS ACTIVE light comes on and car feels like your stopping on ice. As expected the car calls NO JOY and shuts down the systems.

Got back home raised car unplugged wheel sensors gave them a spin they all seem to make give or take the same voltage as there mates both front both rears. I jumped the A to G and got the following codes

SYSTEM 1 CODE C-12
SYSTEM 4 CODE H-68 this one doesn't shock me my A/C system is a mess but works. from what I have read this is a A/C relay problem
SYSTEM 9 CODE H-31
SYSTEM 9 CODE H-31

opened up the FSM ran the trouble flow chart car passed all test in flow chart all the way down to plug in Tech 1

I do plan to clear all code later today.

Input would be Appreciated these parts are not cheap

Did you check for wheel bearing play?

Have you looked inside the ABS compartment and verified no water has filled the compartment?

Have you reseated connector C413 (items 4 in the diagram) that's the connector where all the wheel cylinder wiring comes into the ABS compartment?

Have you reseated the main ABS connector (item 2 in the diagram) that goes to the ABS Module?

What was the voltage from the rear sensors? (greater than .3 volts AC)?
Did the air gap appear to be the same for the other rear sensor?

If you clear the code does it come back immediately when the vehicle starts moving?

Looks like you could re-pin the wiring of the rear sensors from left to right and right to left rear sensors at C413.
If the problem follows the sensor you know it or the wiring is bad and not the ABS module.

 

[forrest]

Did you check for wheel bearing play?

Have you looked inside the ABS compartment and verified no water has filled the compartment?

Have you reseated connector C413 (items 4 in the diagram) that's the connector where all the wheel cylinder wiring comes into the ABS compartment?

Have you reseated the main ABS connector (item 2 in the diagram) that goes to the ABS Module?

What was the voltage from the rear sensors? (greater than .3 volts AC)?
Did the air gap appear to be the same for the other rear sensor?

If you clear the code does it come back immediately when the vehicle starts moving?

Looks like you could re-pin the wiring of the rear sensors from left to right and right to left rear sensors at C413.
If the problem follows the sensor you know it or the wiring is bad and not the ABS module.

Thanks for the reply I just went and once again reseated all plugs and gave a road test same thing does the ABS test cycle and keeps doing it until it does the system shut down. I plan on giving the car full attention hopefully this week end if I can find the time, weather is falling apart rite now. as for one of your questions the voltages were Front .3 volts plus hand spun tire. .5 volts plus rear engine driven. it seems what ever tells the pump to do the cycle keeps telling it to do the cycle.

 

[ecss]

Thanks for the reply I just went and once again reseated all plugs and gave a road test same thing does the ABS test cycle and keeps doing it until it does the system shut down. I plan on giving the car full attention hopefully this week end if I can find the time, weather is falling apart rite now. as for one of your questions the voltages were Front .3 volts plus hand spun tire. .5 volts plus rear engine driven. it seems what ever tells the pump to do the cycle keeps telling it to do the cycle.

Manual says every time the ignition is turned On and vehicle not moving a static resistance check is done on the wheel sensors. For instance code DTC33 would set if the RR sensor continuity check failed.

When the vehicle speed reaches 4 mph or more a dynamic ABS check is done and the signal from the wheel speed sensor is examined and DTC 31 will set if something is wrong with the signal from the RR wheel speed sensor.

Have you verified the tip of the sensor is clean?

I'd guess the sensor is bad. One way to verify is to look at the signal with an oscilloscope and compare it to the left rear sensor.

No scope or Tech 1 not much you can do except guess. :gap

 

[forrest]

Manual says every time the ignition is turned On and vehicle not moving a static resistance check is done on the wheel sensors. For instance code DTC33 would set if the RR sensor continuity check failed.

When the vehicle speed reaches 4 mph or more a dynamic ABS check is done and the signal from the wheel speed sensor is examined and DTC 31 will set if something is wrong with the signal from the RR wheel speed sensor.

I'd guess the sensor is bad. One way to verify is to look at the signal with an oscilloscope and compare it to the left rear sensor.

No scope or Tech 1 not much you can do except guess. :gap

OK I will give the right rear a good look, anything is possible, a few weeks ago I did hit a hell of a pothole hidden in a puddle. I will get the wheels off the ground and give the wheels another shake and look. I did try to get the sensor's out but they are a bit stuck, and until I had more than a hunch I didn't want to force or really give a hard effort.

thanks

 

[forrest]

OK I will give the right rear a good look, anything is possible, a few weeks ago I did hit a hell of a pothole hidden in a puddle. I will get the wheels off the ground and give the wheels another shake and look. I did try to get the sensor's out but they are a bit stuck, and until I had more than a hunch I didn't want to force or really give a hard effort.

thanks

I just read through the flow charts for the trouble code, and I now have a battle plan but it still seems that this is more a problem that yes is a problem but is it one that would leave the ABS pump running while the car is in motion. on queue as soon as the car hits the magic 4 MPH as one would expect you should get the ABS test 1 time, not the case here the pump runs until you stop or the system shuts down.

 

[ecss]

I just read through the flow charts for the trouble code, and I now have a battle plan but it still seems that this is more a problem that yes is a problem but is it one that would leave the ABS pump running while the car is in motion. on queue as soon as the car hits the magic 4 MPH as one would expect you should get the ABS test 1 time, not the case here the pump runs until you stop or the system shuts down.

Since only DTC 31 is setting, I'd ignore what ever the pump is doing.
If you look at page 5E2-4 System Self test it says during the automatic self test it cycles each solenoid valve and the pump motor as well as necessary relays to check component operation. If an error is detected, the EBTCM will set a DTC. Another words the EBTCM monitors the state of the relay that turns on the pump.

At connector C413 is there any way you can poke the wires out at the connector and move the two wires for the left sensor to the right sensor wires and the left sensor wires to where the right sensor wires go? Then see when you drive the vehicle if the DTC moves to the Left side?

DTC 31 appears to be setting because something is wrong with the frequency of the signal from the RR sensor.

I'm assuming you're saying when the DTC sets the system is disable and is indicated by the Service ABS and ASR indicator lights coming on.

 

[forrest]

Since only DTC 31 is setting, I'd ignore what ever the pump is doing.
If you look at page 5E2-4 System Self test it says during the automatic self test it cycles each solenoid valve and the pump motor as well as necessary relays to check component operation. If an error is detected, the EBTCM will set a DTC. Another words the EBTCM monitors the state of the relay that turns on the pump.

At connector C413 is there any way you can poke the wires out at the connector and move the two wires for the left sensor to the right sensor wires and the left sensor wires to where the right sensor wires go? Then see when you drive the vehicle if the DTC moves to the Left side?

DTC 31 appears to be setting because something is wrong with the frequency of the signal from the RR sensor.

I'm assuming you're saying when the DTC sets the system is disable and is indicated by the Service ABS and ASR indicator lights coming on.

UPDATE

I finally got a chance to take a look shake the hub bearings and get a volt meter back on the car, it all boils down to a problem with right rear sensor has a problem. the sensor itself checks ok making 0.5 volts 940 Ohms

so hopefully I will get a chance to run the rest of the chart and confirm a voltage reading, I had a reading of 18.5 mv and 0.5mv volts on the plug ends of the harness side on wheel senor and I want confirm with a better DC volt meter it was ranging all over the place

because at this point it would be difference between a EBTCM-SWITCHED MALFUNCTIONS or a other path.

I have a good replacement sensor from a friend that I will be throwing I soon, only because i was tapping on sesor with a punch and hammer to get it unstuck (didnt really move) but after the light went away for a hour.

 

[ecss]

UPDATE

I finally got a chance to take a look shake the hub bearings and get a volt meter back on the car, it all boils down to a problem with right rear sensor has a problem. the sensor itself checks ok making 0.5 volts 940 Ohms

so hopefully I will get a chance to run the rest of the chart and confirm a voltage reading, I had a reading of 18.5 mv and 0.5mv volts on the plug ends of the harness side on wheel senor and I want confirm with a better DC volt meter it was ranging all over the place

because at this point it would be difference between a EBTCM-SWITCHED MALFUNCTIONS or a other path.

I have a good replacement sensor from a friend that I will be throwing I soon.

An oscilloscope would confirm if there was a signal problem.

 

[forrest]

An oscilloscope would confirm if there was a signal problem. [/QUOTE


I got my hands on a good sensor, it was a uphill battle getting the old out with all of its 20 plus years of corrosion it accumulated with its previous life with its first owner in Illinois, cleaned up the knuckle and Anti seized real good assembled 2 days later I can finally say FIXED