North American Turbocoupe Organization



ABS wheel speed sensors...
Kuch Offline
Member
#1
So my 88 TC has the yellow ABS light on, but the red brake light is off. When the key is turned on, the pump runs and pressurizes the system, I did put a new relay in it just to do it. According to the tech article on this site, the ABS computer is either not powering up, or found a fault and shut it off. I'm thinking I may have a bad wheel speed sensor on one of the wheels. So, my question is where are they located? I can't find anything online about locations or replacements available, anyone here have some info? Thanks
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof, T3/T4 50 trim, 255LPH, BBK AFPR, 3" DP dual 2.5", MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
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Jeff K Offline
Administrator
#2
You can run a self test on the ABS computer and watch the ABS light flash out any codes.

Best way to check wheel speed sensors is to drop the panel behind the rear seats and pull the 30 pin plug off the ABS computer. Locate the feew for one wheel sensor, say the left front. Hook a DMM set on AC millivolts to the speed sensor terminals at the ABS computer. Give the wheel a hard spin. Sensor should output 100 to 250 mV, depending on how fast you spun it. Repeat for the other 3 wheel sensors.

If you find a dead one, likely cause is a break in the coax like cable running from the wheel sensor to the ABS computer. Remove the sensor, and look for breaks, weak spots, etc in the coax like cables. The cables are long enough that a break can be cut out and the cable spliced together.

AFAIK, replacement ABS sensors an not available anywhere.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Kuch Offline
Member
#3
Thanks for the reply Jeff, I figured they were not available anymore as I couldn't find any online. I'll have to get underneath it and start checking the wires. I tried in the fall before I parked it for winter to pull the codes from the ABS test plug in the trunk, but it never sent any codes, no matter how I jumped the pins. Not sure why that is doing that though.
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof, T3/T4 50 trim, 255LPH, BBK AFPR, 3" DP dual 2.5", MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
Reply

Jeff K Offline
Administrator
#4
No codes is either incorrect attempt to get the codes out, or ABS computer not powered up. With key in RUN, check for power and ground at the ABS computer with a test light.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
Reply

Kuch Offline
Member
#5
Thanks for the idea on checking power to the abs computer in the trunk. I have an old Chiltons manual for the car and I Have been reading the wiring diagrams for the ABS, as far as I can tell, pin 513 br/pk wire should be power from the relay in the engine bay to the computer. Can you confirm this, I am not the best at reading these diagrams, but I think that's right.
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof, T3/T4 50 trim, 255LPH, BBK AFPR, 3" DP dual 2.5", MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
Reply

Kuch Offline
Member
#6
Update, I went out this morning and checked the power to the ABS computer in the trunk. I went with pin 513, the Br/Pk wire with the key on engine off. I had power to the connector going to the computer, checked with a light. I also double checked the tester connector again by installing a jumper in the bottom two pins and key to run and still did not get any codes flashing. This leads me to believe that the computer is bad as I have power to it and cannot get any codes. Thoughts?
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof, T3/T4 50 trim, 255LPH, BBK AFPR, 3" DP dual 2.5", MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
Reply

Jeff K Offline
Administrator
#7
It is possible the ABS computer is bad, but I have never heard of one failing (which really doesnt mean that much). I have seen them on Ebay a few times.

Might be worth taking it apart and looking for obvious damage, like burned traces on the circuit board, blown electrolytic capacitors, etc.

Several years ago, I was given a LA3 EEC for free because it didnt work. Opened it up, and found a burned trace on the board. Fixed the burned trace, and it was good as new. Now I have a spare. You might get lucky and be able to fix yours.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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