Pinout Box (for troubleshooting ABS System)

[Guest Kitskaboodle]

Padgett, will give you pinout numbers when I get home. (at work now)

Test "F" is near the back section of the ABS trouble code section in the FSM.

Walt....yes, that's that's my multimeter exactly!

Oh, and are you implying my car's name is "Linda Blair"?

MC_Reatta...As I had mentioned previously, 90 wheel sensors are non-adjustable. I measured the gap between the inside of the drivers side wheel sensor and the toothed ring and I got .040 Padgett had mentioned it should be .020 so my gap is double that. FSM says nothing about this gap other than it's factory pre-set.

Can someone (who has a 90) and measure their gap so we can compare numbers?

Thanks, Kit

[padgett]

I would not think .040" would be a problem.

The problem does match a proper resistance at POST (yellow light goes out after startup but comes on over 13mph (believe it starts checking for a mismatch in the sensor readings then).

[Guest Mc_Reatta]

Thinking a little outside the box, wonder if you can take out one the rear sensors and install it at one of the front wheels and see if you can generate a voltage with it in place. Some people have said that they may not come out cleanly, so not sure if you'd want to take a chance by taking a good one out.

Sensors are supposed to be the same all around, but the cable configurations are probably quite different front to back.

That would at least confirm that everything else is working OK except the front sensors.

Would not need to connect the sensor plug up to the one under the hood if the cable isn't long enough as long as you can get your meter probes into to it to look for the AC voltage. Would need to probably get it up to speed by rotating the wheel vs. driving the car though.

[Ronnie]

FSM says the sensors cannot be swapped front to rear.

[padgett]

Well sorta. The rears have the mounting hole 180 degrees from the cable, fronts are 90 degrees. Other than that they seem to be the same depth and diameter.

[Guest Kitskaboodle]

I do have some spare used 88 front sensors. (with brackets)

The reason I havent tried these is because

A) the ABS light has been on since I owned the car

BRAND NEW factory wheel sensors on the front didnt

cause the light to go out at all. (i.e no change)

Even though the 88 sensors fit into adjustable brackets

are they physically & electronically the same as 90's?

If needed, I can put in the used ones and see of there is any change

but as mentioned I dont know why it help.

Kit

[padgett]

AFAIK the Teves sensors did not change 88-90. If the ABS light is always on and there is no "thump", you have a power problem, not a sensor one. Can verify by trying to pull codes. You won't.

[wws944]

AFAIK the Teves sensors did not change 88-90. If the ABS light is always on and there is no "thump", you have a power problem, not a sensor one. Can verify by trying to pull codes. You won't.

We did get EBCM codes. Jumpered the pins on the ALDL connector, counted blinks. Kit has also tried several EBCMs to no avail.

Is it possible that the PO might have swapped hubs, and put something in that was incompatible with the stock sensors? It is weird that there would be no signal from *both* sensors.

Edited October 26, 2010 by wws944 (see edit history)

[Guest Kitskaboodle]

"Which "F" chart and which pins have no continuity ?"

OK...I will answer your question above.....

Here is the test results for Codes 31 & 75 (left front wheel sensor)

(FSM says 800-1400 ohm is acceptable range)

1st test : Pinouts 5 & 23 1.060 ohms according to my meter (is this 1060 ohms?)

2nd test: Pinouts 1 & 23 No continuity

3rd test: Pinouts 1 & 5 No continuity

FSM then says to go to test "F"

Test "F" Results: (Done while car in motion and a steady 15-16 mph)

(FSM says 50-700 mv is acceptable range)

Left front wheel sensor: Pinouts 5 & 23 .002 (steady / speed doesnt affect it)

Right front wheel sensor: Pinouts 7 & 25 .001 (steady / speed doesnt affect it)

Left rear wheel sensor: Pinouts 6 & 24 .580 (avg. / changes with speed)

Right rear wheel sensor: Pinouts 4 & 22 .330 (avg. / changes with speed)

FSM then says to go to test F-2 (for left front sensor)

and F-4 for right front sensor. Basically these tests keep taking me to the

same place: "Inspect wheel sensor mounting and toothed ring".

Here is the test results for code 45: (missing wheel speed sensor signals)

(FSM says 800-1400 ohms is acceptable range)

1st resistance test: Pinouts 5 & 23 1.060

2nd resistance test: Pinouts 7 & 25 1.043

3rd resistance test: Pinouts 4 & 22 1.083

4th resistance test: Pinouts 6 & 24 1.077

FSM then says to go to wheel sensor test "F" again

and test all 4 wheel sensors.

Lastly, I checked two extra things tonight:

Right front wheel sensor to toothed ring gap is around .035

Did a visual check of the toothed ring (but did not jack the car up so was only able to check about 60% of the circumference of the teeth. They look just fine.

Will jack it up and spin the wheel later in order to check it 100% around.

Thought it would be worth re-capping the initial ohm readings I got for all 4 wheel sensors:

Left front sensor: 1076 ohms

Right front sensor: 1057 ohms

Left rear sensor: 1100 ohms

Right rear sensor: 1100 ohms

My brain is hurting...I need to go to bed now.

Kit

Edited October 26, 2010 by Kitskaboodle (see edit history)

[padgett]

OK that all makes sense and about here I would disconnect the left front wheel sensor and see what new code appears then do the same for the right front.

5-1 and 23-1 are checking for shorts to ground and should read open. Statically, it all looks good.

The book says 31, 35, 41, 55, 75 are all LF WSS. I have not seen 41 or 55 but think 3x is current and 7x is history. I also suspect this is really not the LF. On my 88 the LF was code 36.

See this thread.

Edited October 26, 2010 by padgett (see edit history)

[Guest Kitskaboodle]

OK...will unplug each front sensor (one at a time) take short drive and then read codes. (from ALDL connector) I will do this tonight....

Question: Is it helpful/is it necessary to disconnect battery after each reading so that the computer will reset?

Thanks, Kit

[padgett]

No the EBCM does not reset that way. You readout the codes then drive over (38 ?) mph for a ways.

[Guest Kitskaboodle]

Bad news........

Cant get car to go into diagnostic mode!

Yes, I disconnected the left front wheel sensor as requested and then drove it up to 50 mph, then parked the car, shut the engine off and jumpered the ALDL pins, then turned the key on and the ABS light stays on solid and will not blink!

By the way...I forgot to mention one tiny detail:

Cant remember WHEN it occured (before or after I replaced the IPC) but

there is a square orange light called "Electrical Problem" that has been on for a while now but I dont think I mentioned it. Maybe this is why the car wont go into diagnostic mode??

Anyways, I'm about ready to give up.

I'm getting nowhere with this dang car!

Kit

[DAVES89]

I mentioned this before, but saw no response.

If your EBCM [the unit in the trunk] is not connected properly, you will not be able to read ALDL codes and your anti brake light will stay on.

[wws944]

Disconnect battery, wait a few, reconnect. What happens?

This is a poser... So we have:

* Whatever it is, it is affecting *both* front sensors

* Both front sensors showing plausible resistance - not open.

* No signal from the front sensors to the EBCM

* Neither front sensor showing shorts to ground (at the pinout box) - you tested both wires from each of the two sensors?

It is almost like someone cut the wires and put resistors across them on their way to the EBCM...

[wws944]

It would be interesting to try disconnecting both front sensors. Then, using the BOB, jumper the rear sensors into the front inputs so the EBCM would think it has four working sensors...

[Guest Kitskaboodle]

I mentioned this before, but saw no response.

If your EBCM [the unit in the trunk] is not connected properly, you will not be able to read ALDL codes and your anti brake light will stay on.

OK...will double check tonight to make sure I didnt bend any pins in the

EBCM connector and then re-connect.

Will also disconnect battery for a few minutes to see if that will help.

Thans again, Kit

[padgett]

To me the "thump" (test 7) is important to tell me that the EBCM is working. No thump/constant yellow is usually a power issue (e.g. firewall relay) and you will not be able to pull codes.

BTW disconnecting the battery has no effect on the EBCM: you have to pull the codes, then drive to clear.

[Guest Kitskaboodle]

I mentioned this before, but saw no response.

If your EBCM [the unit in the trunk] is not connected properly, you will not be able to read ALDL codes and your anti brake light will stay on.

Yep......you were right!

Trunk connector to ECBM wasnt properly connected. (my fault)

Ok Padgett.....the results of the test you asked for.......

Disconnected left front wheel sensor, drove car and then came back to read codes: They are in this exact order:

21

12

31

45

75

Plugged left front sensor back in, disconnected right front wheel sensor, test drove, then came back to read the codes. They are

in this exact order:

21

12

32

45

75

They are virtually the same exact for the middle one (31 vs 32)

OK....now what?

Kit

Edited October 31, 2010 by Kitskaboodle (see edit history)

[padgett]

Seems unlikely. 12 is EBCM failure and 21 is the main valve. 45 indicates two simultaneous sensor failures and 75 is Left Front. SOunds very confused. I'd try a different EBCM but have a spare.

[Guest Kitskaboodle]

I have two spare EBCM's.

Will connect them both tommorow and see what codes I get with each.

I bought the two spare years ago. After hooking them up got the same

end result....ABS light coming on after 12-13 mph. So, I put them away

for a rainy day.

Kit

[Guest Kitskaboodle]

OK....per your request Padgett: All code numbers shown are in the order as they were displayed and this test did not include unplugging either front wheel sensor during the test:

EBCM spare#1

Code 27

Code 31

Code 45

Code 75

EBCM spare#2

Code 21

Code 99

Code 31

Code 45

Code 75

By the way, all 3 EBCM's may display different codes but they all have one thing in common....they turn the ABS light on at 12-13 mph and then stay on.

Also, what is code 99?

That number doesnt seem right.

Kit

[padgett]

Good question since no reported Teves code has a "9" in it. Common factor seems to be 31 (LF), 45 (2 sensors) and 75 (LF) which I cannot be certain about. Black car was giving multiple codes on receipt and all went away when I replaced the one bad sensor.

Suspect the next step will require an oscilloscope.

[Ronnie]

Sounds like it would be good idea for someone to build a test bench to check sensors so you could eliminate all the sensors as being the cause of the problem. Then we could send all of our questionable sensors to them for testing. Once they are known to be bad it might be possible to repair them.

The test bench could be as simple as chucking up the end of a half-shaft that has the cog ring on it into a small lathe so it could be spun at a certain speed Then fabricate a fixture to fit on the tool post so you could mount a sensor to it so you could adjust it near the spinning cog ring.

Once you had it all setup to simulate a car in motion you could use a meter to check the output of questionable sensors against a known good sensor to determine if the sensors output was within range.

Yes, you can do the same thing on the car but it is hard to do test on a car in motion or running on jack stands.

[Ronnie]

I have been looking at the FSM to see what could cause the erratic codes that you are getting. Since you have tried new sensors and a number of ECBMs they are not too likely to be the problem

One thing I see that could be causing erratic readings and new sensor to show up as bad would be a bad ground connection that goes to the shielded cables. There could be a bad ground connection at the ground junction box near the battery, or a break in the wires that connect all the shielded cables together. The sensors only produce a small voltage that is detected by the ECBM. If the cable shield is not grounded you could be getting stray signal voltages in the wires created from outside sources such as the plug wires and voltage spikes in the electrical system that would run the ECBM crazy. I would check to be certain the shielding on the wires has a proper ground, especially the front sensor wires since both are close to the engine.

[Guest Kitskaboodle]

Good question since no reported Teves code has a "9" in it. Common factor seems to be 31 (LF), 45 (2 sensors) and 75 (LF) which I cannot be certain about. Black car was giving multiple codes on receipt and all went away when I replaced the one bad sensor.

Suspect the next step will require an oscilloscope.

In case you're wondering I double checked each code TWICE (including the 99 code) and I'm 100% certain they are correct!

Bad news on the oscilloscope......not only do I not have one but even if I did

I wouldnt have a clue how to use it!

Kit

[Guest Kitskaboodle]

I have been looking at the FSM to see what could cause the erratic codes that you are getting. Since you have tried new sensors and a number of ECBMs they are not too likely to be the problem

One thing I see that could be causing erratic readings and new sensor to show up as bad would be a bad ground connection that goes to the shielded cables. There could be a bad ground connection at the ground junction box near the battery, or a break in the wires that connect all the shielded cables together. The sensors only produce a small voltage that is detected by the ECBM. If the cable shield is not grounded you could be getting stray signal voltages in the wires created from outside sources such as the plug wires and voltage spikes in the electrical system that would run the ECBM crazy. I would check to be certain the shielding on the wires has a proper ground, especially the front sensor wires since both are close to the engine.

I did check the ground junction box (just opposite the battery on the passenget side fender well) The lug rings were in great shape!

As for shielding, my front sensors are practically brand new so there shouldnt be any exposed shielding unless you mean somewhere else in the wiring.

It's funny....in all the time I had this car and all the brake system parts I replaced over the years "THE PROBLEM" never went away. No matter what I threw at it, the same issue was still there and is still there today, 4 years later. ("THE PROBLEM" as I mentioned before is the ABS light coming on at 12-13 mph and not going off)

Thanks for the advice & input.

Kit

[padgett]

Lots people in the Sunnyvale/Palo Alto area know how to use an O'scope but I suspect a wiring issue despite the new sensors. BTW the shield is the gound on the sensors and the two conductor wire it connects to is not shielded.

Do you have access to the computer museum at Moffet Field ? (Within sight of the Blue Cube). They would know how (if it is still there...)

[wws944]

Lots people in the Sunnyvale/Palo Alto area know how to use an O'scope but I suspect a wiring issue despite the new sensors. BTW the shield is the gound on the sensors and the two conductor wire it connects to is not shielded.

Lots of folk have 'scopes in their garages around here... Mine is a bit big to be driving around with though. (Tek 7904)

Do you have access to the computer museum at Moffet Field ? (Within sight of the Blue Cube). They would know how (if it is still there...)

The CHM is a terrific place! Have you been there? AFAIK, they don't have 'lender' scopes. (Do know a few people who are associated with it.)

Blue Cube just shut down.

[Ronnie]

BTW the shield is the gound on the sensors and the two conductor wire it connects to is not shielded.

But the FSM shows the rest of the harness to have a shield with a common ground. It shows the following circuits for each wheel:

• Sensor High
  
• Sensor Return
  

And Drain (shield that is common to all sensors connected to ground)

Good luck finding the problem.

Edited November 1, 2010 by Ronnie (see edit history)

[padgett]

At one point before I found the code was pointing to the wrong sensor I ran jumpers from the sensors at the front to the box at the rear. Should be easy with a BOB. Might als examine the wires in the EBCM connector very carefully, maybe there is a short between two sensors.

[Guest Mc_Reatta]

Think this thread is getting to theoretical and not going after the solution to the problem.

Worrying about left front vs right front is pointless since neither front sensor is providing a signal to the EBCM at this point.

Figuring out whether the wiring in the car matches the FSM is easily determined by checking the wire colors at the connectors vs the color of the connector at the ECBM, or by repeating the sensor resistance test for one front sensor, and disconnect the sensor connector under the hood. If the reading goes to infinity, then that is the correct sensor wire. If the reading stays the same then check that the opposite sensor reading is now infinite. Then you know that the FSM has the wiring diagrams backwards.

Even it you prove the FSM correct or not, it won't verify that the firmware in the ECBM is correct in relation to the FSM. The only way to verify this is to have a working system, and pull one of the front sensor connectors. Then read the codes. Either the error code will indicate the correct sensor is not working or it will say the opposite side is not working. That's the only way to prove the ECBM matches the ESM. Kitskaboodle is not in a position to answer this question at this point.

Need to find out if in fact your "new" front sensors are working or not. You have already failed the AC output test, so that is how to track the problem down.

Watch this video on a Honda, and pay particular attention to the AC voltage test that takes place at the 4 min 30 sec mark.

Diagnosing Antilock Brake System Wheel Speed Sensors

You need to do this with a front wheel and see what happens. I suggest unplugging the sensor under the hood and use you DVM to measure the AC voltage right there as you spin the wheel. If you don't get some output it's either the sensor or the toothed gear assuming the sensor to gear spacing is within spec.

[padgett]

I'd still start at the BOB and check for continuity between all of the sensor pins. Obviously something unusual is going on and a possibility is a solder "blob" in the EBCM connector or a short in the trunk harness connecting two wires. The static resistance (ohms) to each pair would be correct as we are seeing but if the two were out of phase when rolling, the a/c signals (millivolts) could cancel out.

[wws944]

I see what you mean, Ronnie. The diagram on page 5E1-88 is really good.

How do the ABS wires route from the front of the car to the EBCM. Do they go under the seats - where water infamously gets in and messes up connections? I wonder if this is related to Kits other "Electrical Problem" light that gets displayed on the IPC?

Is the "Electrical Problem" light in a '90-91 the same as not getting "The Show" in a '88-89?

[Guest Kitskaboodle]

Think this thread is getting to theoretical and not going after the solution to the problem.

Worrying about left front vs right front is pointless since neither front sensor is providing a signal to the EBCM at this point.

Figuring out whether the wiring in the car matches the FSM is easily determined by checking the wire colors at the connectors vs the color of the connector at the ECBM, or by repeating the sensor resistance test for one front sensor, and disconnect the sensor connector under the hood. If the reading goes to infinity, then that is the correct sensor wire. If the reading stays the same then check that the opposite sensor reading is now infinite. Then you know that the FSM has the wiring diagrams backwards.

Even it you prove the FSM correct or not, it won't verify that the firmware in the ECBM is correct in relation to the FSM. The only way to verify this is to have a working system, and pull one of the front sensor connectors. Then read the codes. Either the error code will indicate the correct sensor is not working or it will say the opposite side is not working. That's the only way to prove the ECBM matches the ESM. Kitskaboodle is not in a position to answer this question at this point.

Need to find out if in fact your "new" front sensors are working or not. You have already failed the AC output test, so that is how to track the problem down.

Watch this video on a Honda, and pay particular attention to the AC voltage test that takes place at the 4 min 30 sec mark.

Diagnosing Antilock Brake System Wheel Speed Sensors

You need to do this with a front wheel and see what happens. I suggest unplugging the sensor under the hood and use you DVM to measure the AC voltage right there as you spin the wheel. If you don't get some output it's either the sensor or the toothed gear assuming the sensor to gear spacing is within spec.

OK...I tried to do what you're asking for in your last suggestion.

Here is what I did this evening:

Because I was not able to jack up the car and spin the wheels fast enough

to get any kind of reading I resorted to plan 2. So....I unplugged each wheel sensor (one at a time) put the probes of my multimeter into the pin holes, ran the multimeter wires under the hood and taped it to the windshield so I could read the values while driving. Next I set the meter to AC volts and drove down the street between 12-20 mph to get an AC volts reading. I also did a static ohms test of the wheel sensors (pushing the probes into both pins)

Here are the readings: (FYI..my multimeter is auto ranging so there is only one AC volts setting on my meter as far as I know)

Left front wheel sensor: 1.114 ohms (static test / car sitting and off)

AC voltage .002 to .003 (when driving between 12-20 mph)

Right front wheel sensor: 1.082 ohms (static test / car sitting and off)

AC voltage .002 to .003 (when driving between 12-20 mph)

Anyways...not really sure if this info is going to help but it doesnt cost anything to do it.

Thanks, Kit

[Guest Mc_Reatta]

Proves that neither of your front sensors are working.

If you have checked that your toothed rings on the CV joints are there and not clogged with debris, and that the gap between the ring and the sensor bottoms is within reason to spec, you have defective sensors despite them having the proper resistance. There is also a magnet in them that is needed to induct the voltage into the internal coil, so the resistance test alone is not sufficient to determine that they are working.

A quick spin of the wheel up in the air should give a reading of about 0.050 volts on your meter. Driving down the road it should be much higher.

Find some new sensors and retest.

[Ronnie]

Left front wheel sensor: 1.114 ohms (static test / car sitting and off)

AC voltage .002 to .003 (when driving between 12-20 mph)

Right front wheel sensor: 1.082 ohms (static test / car sitting and off)

AC voltage .002 to .003 (when driving between 12-20 mph)

Anyways...not really sure if this info is going to help but it doesnt cost anything to do it.

Thanks, Kit

That pretty much matches the results you got from your last test (below) that proves the voltage output of the sensors is not within range. Could the new sensors you have be the wrong ones?

"Test "F" Results: (Done while car in motion and a steady 15-16 mph)

(FSM says 50-700 mv is acceptable range)

Left front wheel sensor: Pinouts 5 & 23 .002 (steady / speed doesnt affect it)

Right front wheel sensor: Pinouts 7 & 25 .001 (steady / speed doesnt affect it)

Left rear wheel sensor: Pinouts 6 & 24 .580 (avg. / changes with speed)

Right rear wheel sensor: Pinouts 4 & 22 .330 (avg. / changes with speed)"

[Guest Kitskaboodle]

OK....I will go ahead and try some other front sensors.

I happen to have two spare sets but they are used and

untested. (but look to be in very good shape)

I pulled one of the front sets off an 88 and the other off an 89.

Are they the same for all years or do I need to get front sensors off a 90?

Thanks, Kit

[Guest Kitskaboodle]

Proves that neither of your front sensors are working.

If you have checked that your toothed rings on the CV joints are there and not clogged with debris, and that the gap between the ring and the sensor bottoms is within reason to spec, you have defective sensors despite them having the proper resistance. There is also a magnet in them that is needed to induct the voltage into the internal coil, so the resistance test alone is not sufficient to determine that they are working.

A quick spin of the wheel up in the air should give a reading of about 0.050 volts on your meter. Driving down the road it should be much higher.

Find some new sensors and retest.

Regarding the condition of the toothed rings I had mentioned in a previous post the air gaps (which were .040 drivers side & .035 passenger side)

and that there was some slight dings to the very edges of two teeth which I filed down and made smooth (on the driver's side ring) Other than that both rings looked to be in good shape.

Thanks, Kit

[Ronnie]

OK....I will go ahead and try some other front sensors.

I happen to have two spare sets but they are used and

untested. (but look to be in very good shape)

I pulled one of the front sets off an 88 and the other off an 89.

Are they the same for all years or do I need to get front sensors off a 90?

Thanks, Kit

I think they should work on the '90 but don't know for certain. Be sure to do the same voltage test as before. Don't depend on the ABS light going out to tell you if the sensor is good or bad.