ABS Trouble.. checked everything please help

ASSISTANCE Suspension, Brakes & Wheels
1

Hey all, I have dont lots of searches but cannot find a solution or anyone that has had this trouble before.

My ABS light is on, yes I realize I could take the bulb out etc… but I would like to fix it rather then just Band-aid the situation.

Anyways I am getting Code 7-4. Which points to a Rear Solenoid or Rear Fail Safe Relay.

So I follow the troubleshooting from the Helm Manual, it has me check the Ohm between the terminals directly on the solenoid.
It is 3 ohm. (which is normal) accoring to the Helm

I check the front ones also and they are the same result.

The fluid level is normal.
I have a second ABS computer, so I switched them and it still shows code 7-4 which somehow tells me the ABS-ECU is working.

So I unplug the harness and check the wire End to End for Continuaty and everything looks fine, I get continuaty properly from the Rear Fail Safe to the ECU.

THe next step is to check the blueish wire from the fail safe to the Solenoid, this also checks out fine. Continuaty is okay.

The only thing I have not tried is to swap the Modulator (which I have a spare from a wreck, that I saw was working).

I have about 5 fail safe relays, so I hook up some wires direclty to the relay and you hear a big click, as the book mentions, there is no continuaty until I hook up power. this indicating that the relay is working fine. I have even tried to switch a few, and nothing.

I am at a total loss.

Ohh I guess another thing I have not tried is to bleed the ABS system.

Does anyone have any thoughts that I can try on this repair? Maybe running a wire from the Harness in the back to the Rear Fail safe? just for a test?

ANy help is appreciated.
(BTW- The car is a Canadian Black 93 GS-R)

2

Wanna sell the car? Bleeding might be a help, has anything been changed on the brake system lately? I am not an electrical system expert, but changing/cleaning the sensor on the wheel may yeild results. Sorry I can’t help more.

3

not yet

sorry I dont want to sell the car, unless the money was good enough to buy another car.

if you are serious email me and maybe we can chat

4

I had this problem… if the selenoid is 3 ohm, then it is OK. the problem is in the relay, it is toast. right by the batery, there are 3 relays covered in the black rubber housing. I do not remember which is rear fail safe relay, but you can swap one or the other and when the code changes, you know which one is bad(just use logic to determine ).
ABS ECUs rarely go bad.
so, just swap those relays, or hit me with email, I will take a pic and send it to you where to look for those thingies.

5

tried the relays

I have actually tried differant relays.

The Helm indicates that the Rear Fail safe relay is on the ORANGE Plug. I called the dealer and all 3 have the same part numbers. So I assumes I can swap them around.

I actually tried to do this, and the ABS Code Remains 7-4.

I even tried one of the spare relays I got from a wreckers and I still get code 7-4.

I have tried that logic.? Got any other thoughtS?

6

The cold TO weather has caused this problem. The only way to fix it to let me take the car to CA and let her sleep in my garage.

7

It actually happened in the summer

The problem has ben happening since the summer, but as mentioned before the car can be for sale for the right money. It seems eveyone wants the black gsr.

8

after swapping the relays, did you reset ABS ECU by unpluging ABS Fuse nr2 or whatever it is…

if so, then take out your multimeter and trace wires from relay back to ABS ECU… God, I remember I even resolder inputs on ECU trying to find fault location, until found that dumb relay being sad.

the last choice, find somebody with GS and borrow ABS ECU to see if iyours does not give you crap…

Wish you best…

9

tried that

After I did all that checking, yes I did reset the ecu, by removing that fuse (alb2) for aprox 30 seconds.

I also have a spare ecu, which has been added to the equation. Did not change. The same code showed up. I thought that would fix it foresure.

I am gonna start by bleeding the thing. Hopefully within the next few days. Then I will check resistance. If that does not fix it I may run wires from the ECU directly to the relay… just to see if the continuaty is actually good.

10

Did you ever get this fixed?

I’m throwing the same codes 7-4. I had trouble compressing one of the rear calipers. after that it started throwing codes.