I have a 1991 Ford F150 I6 4.9 with RABS. I have been reading through the threads on how to bleed and that appears to be no big deal. Passenger Rear, Driver Rear, then ABS Hydraulic module. My question is how to check for proper operation of the ABS Hydraulic Module under the cab and the ABS module under the dash. Without specialized tools but a volt meter. Can someone point me in the right direction how to diagnose and ID a problem. I am in the process of restoring the back end with fuel tanks, and will be replacing brake lines. I would like to check things out prior to putting parts back together. I have looked at Chilton and Haynes along with the Ford service manual for this year of truck with no luck. My rear ABS rear sensor (axel) is working properly. I have an ABS light (on) inside the cab with no ECC code.

Thanks

Tim

 

RABS Codes
courtesy of Steve83

Follow the instructions posted there for how to obtain the RABS codes from the control module. They are not stored in the ECM/PCM.

 

Where are those instructions? I do not see a link.

 

clicky----> RABS Codes

It's a hyperlink.....

 

How you check for proper operation of the ABS is a road test where you slam on the brakes, along with the prove out of the warning light
Although, you might read of an ABS module bleed function in the book, you do not need to do that ever unless you have an old Super Coup Thundernird and replace the HCU
Your truck with RABS can be bled conventionally with no RABS valve bleed procedure. You do not even need to touch the RSABS valve bleed screw unless you replace the RABS valve
Yes, flash out the codes by grounding the wire
Know that if the module is no good, it will not flash out codes
I used to have to put a new module on a few of them, then perform the flashout test and replace the RABS valve
Have fun, good luck

 

Hello was able to get the Codes off my ABS system on my 1991 Ford F150. It flashed 4 times. The Manuel says that the RABS Valve switch closed. I have the instructions to test this. My question is if I find that the ABS valve is bad. Should I buy a module from a salvage yard and hope it works for a while or get a remanufactured. Is it possible to send this off to be remanufactured.

Thanks

Tim

 

You will get a reman from a parts store and they will take yours back as a core to rebuild
You might be able to find a rebuilder to send yours to
The cores are expensive
Last one I replaced, they wanted 125 for the core

 

Im troubleshooting my ABS system now. I had a 4 flashes code. I checked my ABS Valve and it appears to have the proper ohms. The next step is to check the wiring harness pin no 6. I cannot find the ABS module. I looked to the right of the pedal and did not see it. I read some post which said to look behind the glove box. I have not found this module. Any suggestions for a 1991 Ford F150.

Thanks

Tim

 

Yes, look behind the glove box
Looking for a black metal box
Sometimes a yellow metal box
Bolted in with 2) 7mm head / T20 Torx screws

 

Hello I was able to get a Flash out code 4 while checking my system. I need some advice on my Multimeter finding.

Test 4A and 4B on the 20K scale I was not able to get a reading on the multimeter. I had a good ground and was in the correct pin. I tested my new module I purchased and had the same results. Am I doing something wrong?

Test 4c I got a reading of 38.8 on the 200K scale.

I tested the continuity between pin 6 and the pin for the ABS hydraulic module and had good continuity.

Im trying to determine if I need to replace the hydraulic module. My goal is to learn to troubleshoot correctly so any advice would be appreciated

Thanks
Tim

 

The electronic module is what they are referencing, not the hydraulic valve on the frame
You need to read between the lines when testing the modules and doing the pinpoint tests
I got a 89 T bird super coup to fix as a possible lemon law complaint car, at the dealer back in the day
The car came with a new 3200 dollar HCU installed
I ran through the pinpoint tests for the code I had and it said to replace the HCU
I replaced the HCU again
Same code, same problem (abs lamp on at 14mph every test drive) (lamp off until I hit that road test speed every time)
Ford engineer got involved, did his own testing, came back to me and said let's replace the HCU
I told him that would be three then
He bowed out basically, and was ready to accept the lemon law buyback
I was talking to the owner / customer the whole time
I ended up taking the car home for about a week, driving it and working on it at my house with a few shots of whisky
Told the guy I would drive it into the dam for him if necessary
Ended up being a ground wire to the module that had 3 ohms to ground, and the spec was 1.8 ohms
I hooked up a jumper wire real quick and road tested it, it was (fixed)!!
Those pinpoint tests are good but not foolproof
There was no ground testing in any of the tests associated with the problem that super coup was having
So read between the lines,
What was happing to that SC was, when 14mph happened, the HCU commanded pump operation to pump up the accumulator pressure
It would not because the ground was not good enough through the module, to ground the circuit to run the pump in the HCU

 

thanks for the great information. How would you suggest I troubleshoot this.

Thanks

 

Without doing the actual testing myself, I would plug in another known good RABS valve
I would also plug in a known good RABS module
At least yours outputs a code (flashes out a code)
DVOMs are not known for being unreliable but
The leads are. I have nails (yes nails) brazed to nuts I have screwed on to my DVOM leads
Those nails provide me with a good contact, and I have less false readings
The chrome on my expensive as hell test leads was screwing me
Pretty hard to find good used spare parts these days (at the dealer, it was easy) back when those trucks were everywhere
I would assume your wiring is good
I have replaced over a thousand RABS valves for solenoid resistance value failures and a few modules over the years
I do have both in my toolbox, to this day for testing
I believe some of that ABS testing is bunk straight out of the manuals, and we used to go back and forth a few years to make sure the pinpoint tests we were doing actually made sense
IMO most problems with RABS 1 and RABS 2 is the ability of the valve to dump brake pressure through the solenoid valve
That will not happen if the solenoid coil resistance is out of spec
I have gotten bad RABS valves from Autozone Et al.
Last one I was fighting with a bad valve out of a Cardone box, I panicked and went to the wrecking yard and got one that was good (to save my sanity)
I temporarily installed that used valve then fought with AZ about the faulty part
I would go through the tests one more time
I would sand down your test leads and remove some of the possibly oily chrome