ABS issues

[jepherz]

I just got a car back on the road, '92. The car had working ABS when I first had it running on a lift. After powerwashing the entire car and doing a bunch of other work on it, I saw that the ABS light is now on and ABS doesn't kick in at all.

The light flashes about 3 times when the key is first turned to the "ON" position, then goes out for about a second, then comes on solid.

I checked the two fuses by the battery, removed and cleaned the sensors on the front wheels, and removed and reinstalled the plugs that are on the ABS unit. The brakes were also bled to remove the horrible smelling, black fluid that was probably 17 years old.

Anybody here ever fixed any ABS issues or have what I'm trying to describe happen to their car?

Thanks a bunch!!

 

Did you check the abs computer in the trunk? It might have gone south. I got rid of my abs, due to the fact with a old car ive heard people have issues with the abs all of a sudden kicking in while driving and became quite a problem. Do you really want to keep it? You should look into ditching it, as the pump weighs a good amount and it is just 1 less thing to go wrong in these cars.

 

Sounds like a malfunction with the ABS computer. However, when you bled the brakes did you also bleed the ABS pump? That is required to bleed the brakes properly and is often overlooked.

 

[CarRacer]

Is it necessary to bleed the pump if you use an air powered canister bleeder? I used one on my car, and haven't dicked with ABS before.

 

[iceman69510]

I have used a vacuum bleed many times on my GVR4 and other vehicles with ABS and never had to bleed the pump separately.

Maybe some body can loan you a '92 control unit to try?

 

[Brunoboy]

this happened to my car the other day. but then it shut off and i havent seen the light since lol.........

 

Quoting iceman69510:
I have used a vacuum bleed many times on my GVR4 and other vehicles with ABS and never had to bleed the pump separately.



You can bleed the brakes without doing the pump and not have a problem, but when there is a problem its definitely something to try, especially if the problem started after a recent bleed.

 

[jepherz]

Yes, I want to keep the ABS as this will be a daily driver if anything and I don't want to modify it from stock much. No, I didn't bleed it at the pump but the ABS light was on before I bled the brakes anyways.

Anybody know if a '91 control module will work in a '92? I already pulled the abs pump from my '91 but still have the control unit in the trunk...

 

Have you tried pulling the error code form the ABS computer? You do it the same way as the VFAQ way to check ECU codes, by grounding pin #10 of the diagnostic port, except its a different pin that the code blinks out on, pin #4.
The code would help a lot.
Checking Error Codes

 

[curtis]

Mine did the same thing about 2 months before I tore here down. I check the wheels sensors with a multimeter and also cleaned all of those , replaced the abs computer with a known one and also powered up the unit by bypassing everything and straight wiring it and the motor does come on but still have the light.

I do have an extra abs unit from a TEL but not sure if there the same but the car has a Q45 master and is getting 4 piston front calipers from a stealth RT so probably will ditch unless something easy works with it. Try the things I mentioned above and might get lucky and find a bad wire somewhere.

 

[jepherz]

Quoting keydiver:
Have you tried pulling the error code form the ABS computer? You do it the same way as the VFAQ way to check ECU codes, by grounding pin #10 of the diagnostic port, except its a different pin that the code blinks out on, pin #4.
The code would help a lot.
Checking Error Codes



I did try this, and from the best that I could tell, it put out L-L-S-S which is 22. 22 corresponds to a bad "STOP SWITCH" which would be the signal when you press the brakes. However, I checked that pin on the harness and it is indeed getting 12v when the brakes are being pressed. I think my only option now is to find a known, working '92 ABS computer. Anybody got an extra?

 

I'm pretty sure I still have mine from when I removed it, but I'd have to look around; it might still be in my parent's garage. Mitsubishi changed some things in the ABS system from '91 to the '92 models so I don't think a '91 ABS ecu would work in a '92 but I'm not sure.

 

[toybreaker]

Jeff, pm me a shipping address, and I'll get one out to you asap.

edit Running the car with all four wheels off the ground on a lift will sometimes confuse the control unit a schosche, as the wheels will turn at vastly different speeds.

If you touched the brakes with the wheels at different speeds, it may have freaked the control unit.

Have you disconnected the battery since you played lift racer?

Many times, that will clear the memory and re-set the unit, and might return it to normal operation.

 

[jepherz]

Quoting Qship:
I'm pretty sure I still have mine from when I removed it, but I'd have to look around; it might still be in my parent's garage. Mitsubishi changed some things in the ABS system from '91 to the '92 models so I don't think a '91 ABS ecu would work in a '92 but I'm not sure.



Yup, '91s have a completely different part number and the ECU case is even different. I've always heard that the '92s have "diagnostics", so I don't know if that means a '91 can't output troubleshooting codes or what?

John, I really appreciate it. I actually still have the ABS ECU in my '91 that I'll try out sometime today (Completely forgot about that!). If that doesn't work, I'll PM you. I'll also try disconnecting the battery and taking the car on an actual drive today. Thanks again for your help, guys!

 

[iceman69510]

Don't put the 91 in the 92 (ECU). The connector wiring is not even the same.

92 VR4 controllers supersede to the same one used on 92-94 1gs with ABS.

 

[jepherz]

Damn, won't be doing that then. Don't the DSMs have different rear teeth count?

 

[iceman69510]

Different count yes, but same front to rear.

The key is 92s are 1:1 ratio whether 43/43 (VR4), or 47/47 (DSMs).
That is all the controller is looking for. That is why 5 lug swaps (complete) onto 92s can retain ABS easily.

 

[jepherz]

Ohh, it's 91's that are way off?

 

[iceman69510]

'91 uses a 2:1 F/R ratio on GVR4s, with 86 teeth front, 43 rear.

 

[toybreaker]

Found the the flow chart for dtc22.

The code sets under two conditions.

1.) Stop light switch may remain on for more than 15 minutes without the abs functions (verbatim /ubbthreads/images/graemlins/tongue.gif )

2.) The harness wire for the stop light may be open

According to the diagram, the brake light switch *may* have more than one set of wires/contacts.

You want to test the green wire at the switch. (green/white is the supply wire)

The green wire should go hot with the pedal depressed.

Since the stoplights work, (?) it's very likely (hedge, hedge... /ubbthreads/images/graemlins/grin.gif ) all's good up to, and at, the switch, and the problem is downstream of teh switch.

You should be able to go the brake switch imput wire at the ecu and verify the wire integrity back the brake switch.

Now, just to bake your noodle a little, those wily engineers ( /ubbthreads/images/graemlins/mamolu.gif ) changed the wire color for the brake "on" signal wire to the abs ecu from solid green back to green and white at the splice where the ecu "brake on" input for the abs ecu splits off the stoplight feed... so...

At the ecu connector in the trunk, unplug it, and go to the green/white wire at the abs ecu connector, pin 29

With the brake pedal depressed, there should be `battery voltage there, (and no voltage with the pedal relaxed.)

So, easy, peasy...

check that teh switch works, then check pin #29.

Power at the switch and not at the ecu = wiring issue

Power at the switch and at the ecu = ecu issue

Ecu part number MB903852 list price $1330.98 /ubbthreads/images/graemlins/ooo.gif

(Damn, I wonder how many of us have used them as wheel chocks over teh years... /ubbthreads/images/graemlins/rofl.gif )



Hope that helps!