North American Turbocoupe Organization



Help with ABS relay diagnosis, please!
evintho Offline
Senior Member
#1
Just got it and already asking for help! I ran the ABS relay diagnosis from the FAQ's. I jumpered the T/Y & GY/R terminals and the pump motor ran with the key both OFF and in the RUN psition.

Put the relay back in, turned the key to ON and pressed the pedal several times, the motor didn't run.

Probed the PK/LB wire and with the key ON grounded the wire - pump motor ran.

It was a little different than the FAQ write up but it sounds as if the relay is good. What's next? Pressure switch? If so, is that a Ford only item or can I grab one at NAPA or Autozone?
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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Pete D Offline
Administrator
#2
There are past posts on testing the pressure switch.

http://natomessageboard.com/cgi-bin/ulti...605#000003
http://natomessageboard.com/cgi-bin/ulti...510#000003
See JT here
http://natomessageboard.com/cgi-bin/ulti...866#000007
Pete Dunham


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Jeff K Offline
Administrator
#3
Could be the press sw. Before spending $150 on a new one, remove the connector from the pressure switch, and jumper the PK/LB wire terminal to the ground terminal of the press sw. I forget the color of the ground, but you can locate it with a DMM easily. If jumping those 2 pins at the press sw gets the motor to run, the problem sounds like the press sw.
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.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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evintho Offline
Senior Member
#4
Found the problem! The tiny plastic tang that holds the PK/LB wire into the pressure switch connector broke off, consequently the wire pushed out the back and wasn't making a connection. Put it back in and dabbed a bit of 2-part epoxy in the back of the connector to hold it. Problem solved!

NATO membership - best $20 I ever spent. Just saved me $150 on a pressure switch! Also, found the reason the aux fan was on all the time. PO had it wired directly into the coil! Thanks Pete D! He must've wired it for a reason. Is there any way to test the IRCM?
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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Jeff K Offline
Administrator
#5
Get rid of that aux fan directly wired to the coil right away unless you like burning up the harness. The fan draws lots of current that the coil power circuit was not designed to handle.

2 ways to test IRCM fan circuits: 1) run KOEO test. 2) Disconnect ECT and jumper terminals in ECT connector. Start motor. Both fans should run.
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.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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evintho Offline
Senior Member
#6
Quote:Originally posted by Jeff K:
Get rid of that aux fan directly wired to the coil right away unless you like burning up the harness.

2) Disconnect ECT and jumper terminals in ECT connector. Start motor. Both fans should run.
Yeah, he had it pushed into the back of the connector on the coil. Now the back of the connector's all melted!
I'm gonna try #2 today. So if both fans DON'T run, does that mean the contacts aren't closing in the relay, hence bad relay?
Trust in the Lord with all your heart and lean not on your own understanding.
Proverbs 3:5

1986 Turbocoupe 5-spd - New daily driver!
1988 Turbocoupe 5-spd - parts car.
1989 Mustang convertible (Thunderstang). Built '88 TC shortblock, head by Boport, R/R, T3, Bobs log, gutted, rotated, ported mannys, AFPR, LA3, NPR I/C, etc.
Check out Thunderstang!
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Pete D2 Offline
Member
#7
If both fans DO run it means the wiring, IRCM, connectors and fan motors ARE OK. If both do not run you need to start checking the above.
Turbo
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