ABS idiot light out of the blue

[Tony H]

Bought this '91 in Sept 2. it hasn'e been registered yet because I am shining up and maintaining years of neglect. I've been starting it up everyonce ina while, after Oil change, after anti freeze change and at other times.
Yesterday I fired it up and the Anti lock brake and brake dash lights came on. Any thoughts?

Fluid level looked good. I'm guessing maybe a Sensor Connector. I've been cleaning and hosing down the wheel wells and engine compartment a lot.

The brakes are fairly new and as I said, the car hasn't left the driveway. Are the connectors to the sensors excessible? I know nothing about ABS, my other cars are too old for these electronic headaches.

 

[boominXplorer]

try resettign the computer, if thta doesn't work it will need the codes pulled

 

[Tony H]

New to the Explorer world. How can I do that besides taking the Neg. off the battery?

I haven't floated around the electronics enough to know where the computer is. I saw a CPU looking item by the passenger headlight.
Sorry to sound so dumb. If it was a Chevy pickup or a Volvo I'd be giving advice not on the questioning end.

I'll get to know this car too soon.

 

[Rhett]

The computer is in the cab; if you sit in the pass. side front seat, it's behind the panel by your right foot. (the kick panel). To reset it, all you need to do is disconnect the negative batt cable for an hour or so. Some say 10 minutes, some say overnight, bottom line is disconnect it for a time. However please note that resetting the computer (Powertrain Control Module, PCM) will not necessarily turn off your ABS light, as the ABS has it's own computer I believe...

The ABS on these trucks (1st generation Explorers, 91-94) and also on Bronco II's (88-90) is really hard to figure out. The ABS light on is VERY common on these trucks. You can search this site for more info. Good thing is that no ABS is not a problem, you can drive around just fine without it.

 

[Tony H]

Battery cable.. OK that's a no-brainer.

Thanks for the location of the Computer.

 

[calbear]

You can buy a Ford code reader at Autozone or Kragens that will also allow you to read ABS codes. I can't remember which store I bought mine at, but it will say on the box if it can read ABS codes or not.

It takes some (but not all) of the guesswork out of the ABS light. On a 93, the plug for the ABS computer is on the driver's side of the engine bay while the engine computer plug is on the passenger side.

My ABS light (93 XLT 4x4) has been intermittent for years. I had it fixed once at the dealer (supposedly they replaced one of front sensors..there is one behind each front rotor and only one for the rear wheels, for a total of three). About 7 months later and beyond the mileage warranty, it happened again.

My code reader says that the front right ABS sensor is bad. But you have to pull the rotor to replace it. Not worth the effort till I have to do a brake job.

In the meantime, electrical tape over the light is working just fine for me....

 

[GSEREP1]

Are you sure that you have to remove the rotor to change the ABS sensor? The sensor is mounted on the back of the wheel hub, and goes through it to read the ring on the brake rotor. It is pretty easy to change.

Thanks

 

[benner31]

it could be a number of things..this happened in my 93 xlt. the abs ecu was bad and needed replacement..it was about $350...could be wheel sensors...could be a bad ground.....i would get a code reader or take it to the dealership!

 

[Eric P]

The '91 should just have rear wheel ABS, like my '92. My ABS light came on when outside temps reached about 100 degrees. Pulled the code and it said it was the control unit. I pulled the ABS fuse and put tape over the ABS light. The system reverts back to a standard braking system. This was 4 years ago, no problem with braking. Just give yourself a little extra room.

 

[JDraper]

The abs light in '91-92 RABS equipped explorers can also be tripped by having too much water in your brake fluid. Brake fluid is hygroscopic, and over time it will absorb moisture. If enough water is absorbed, it will change the density of the brake fluid. This fools the computer into thinking that the pressure is low, and throws the light on. I had this happen with my '92 Explorer, and I have seen it happen in others. I had my system flushed and refilled with new fluid, and the problem went away. It did take a couple of days for the light to go out after the system flush was done. I believe that was because the ABS module is on a dead end brake line, and I think it took that long for all the old fluid in the dead end line to mix with the new fluid.

Before you start replacing components, I would first see what codes are being thrown, and if it's a "low fluid pressure" code, I would then have the system flushed.

You can check most of the codes on your '91 without a code reader. Go buy yourself a Haynes repair manual, and it tells you how to do it. Basically, you jumper two pins on the computer connector under the hood, and the check engine light flashes in a sequence, telling you what the codes are.

 

[GSEREP1]

Can you do that with newer Explorers as well? I finally got mine fixed this week without going to the shop, but it was a shot in the dark, and I was lucky. I was really lost, and I may have had to take it in regardless. I understand that a digital ABS reader is very expensive....about 2 thousand dollars.

I will check with Autozone and see if they have a reasonably priced ABS checker that I could buy!

 

[JDraper]

No, you can't do that with a Gen II Explorer...only those with the OBD 1 computers, which (If my memory is correct) are only in the '91 and '92 models. You have an OBD II computer.

 

[TheJMan]

A slight possibility, but I had a similar problem in my 93 where the ABS light came on because the positive battery cable connection was loose. That and the voltmeter would spike and read around 17 volts (overcharging).