Ranger XLT ABS light - Check engine light

On our way to our daughter's house, pulling an empty flat bed trailer, the ABS light stayed on. That's never happened before. Also, almost to her house, the "check engine" light came on. Could anyone advise? My manual is not in the truck and we're out of town. We're suppose to be helping her move, but am concerned about these issues.

Did the lights stay on?
Did the truck seem to be running or breaking any different?

The lights did stay on. And the truck didn't seem to be running any differently. Except one time, it felt like it didn't want to change gears. It is an automatic. I checked the oil, and transmission fluid....the trans fluid was low. I put some in, but the check engine light and ABS light are still on. Thanks for any help. We are not using right now to help her move, but we will have to drive it back home.

My ABS light came on once, when i had to slam the brakes to keep from hitting a moron who cut me off, it stayed on for about two years after that day. The brakes worked fine, the light just stayed on.
I finally got it to stay off about a month ago, when I changed my back brakes and bled them thuroughly.
Good luck

My advise to you would be not to panic. Check the simple things first. Your brake fluid level and condition, fuses, etc. Try and disconect the battery, wait 30 seconds than reconnect the battery. This will reset the computer (if installed). I'll tell you from experience, that repair shops will charge at least $60.00 just to run a simple diagnostic test, that you can for the most part, do at home.

I have a similar problem with my '89 Ford Ranger. Except I don't have the check engine light stay on, only the ABS and the parking brake lights on the dashboard stay on each time I press the brake pedal about halfway to all the way down. The ABS system still works, I can feel the brake pressure releasing off the pedal.
I'll say this about the first generation ABS systems, they are very sensitive. I little bit of air in the brake lines or even old brake fluid can set off the light(s). Also low fluid level can cause problems.
To keep this message shorter, I replaced every ABS part in my truck. Wear and tear with age wore those parts out. I did not replace the excitor ring inside the rear axle. Close inspection and testing with an O-scope showed the speed senor was sending the voltage correctly. These systems are very diffcult to get the error codes to come on, even when grounding the one-wire test connector under the dashboard. I presure bleed the entire brake system a couple of times. Air can get traped inside the Electro-hydraulic valve. I'm thinking of testing the brake warning Diode/resistor assembly, can't seem to get that part anywhere. The power brake booster is the only other thing I can think of.

It could be the speed sensor on the rear differential. My check engine light also came on, but did so before the abs light. When the rear speed sensor goes out it affects the abs, and therfore turns the light on. It was a relatively easy fix, I think that the part was around $20.

I thought about the same thing once I started having the problem. I replaced the speed sensor twice. I even went as far as to replace the RABS module along with the RABS valve and the master cylinder with the brake fluid level sensor under the plastic reservoir. I checked through my truck schematics, the only thing I found so far was the diode/resistor assembly, which tested OK. This problem is hard to isolate. Does not seem to be intermittent and the two lights only come on when the brake pedal is pressed about half way regradless of speed. I checked the stoplight switch, that's OK. I don't think the emergency brake switch would have anything to do with the RABS system, I just thought about that.

John476-did you ever get an ABS code?

No-I did some research on the subject. I never could get the ABS codes to come on. Its supposed to be a matter of grounding the self-test connector once the light comes on and at just the right time. It's a test that has nothing to do with the main computer, but does show the ABS codes. After several tries, I gave up that option and started trouble-shooting the old fashion way. There's not much left to go on. I suspect a possible vacuum leak at the power booster. I don't have a working tester for that, right now. I ruled out all the parts in the ABS system so far. It's either a electrical problem or a vacuum leak somewhere. Unless my pressure bleed procedure caused damage to the ABS system, I used no more then 15-25psi on the master cylinder to pressure bleed the entire brake system. I might try bleeding the brakes again, this weekend. The brake pads and shoes are new and so is the drums and discs. I Just got done retrofitting a more powerful alternator for the truck.

To check for a leaky power booster, just turn off the truck and wait a minute then push the brake pedal a few times. You should have enough vacuum to get 2 pedal applications with vacuum assist. Then the pedal should start to feel harder.
just to clarify---at startup the lights self test properly? then they go off?, but come on when the pedal is pressed more than half way? and then stay on steady? until the vehicle is turned off? This all started on it's own before any work was done?

To clarify. I start the ignition, the ABS does its self-test, the light comes on for about 2 seconds then goes off (passes, no codes stored). The parking light stays on until I release the parking brake, then goes off. I drive the truck, but once I press the brake pedal about halfway, both lights come on and stay on until I turn off the engine. With the engine off I press the brake pedal down a couple of times, then it becomes stiff. This problem started before I replaced those parts. I replaced those parts in the hope it would solve the problem. The system was a lot worse before, it would fail the self-test and turn off the anti-lock feature. Could there be somthing outside of the RABS system that could set off those lights? I checked all the lines and found no leaks. Pressing the pedal down does not feel spongy, could air still be trapped somewhere?

Do the lights come on even if you push the pedal down while still in park?
IF so, restart vehicle and disconnect the fluid level switch from the master and then push the pedal.
Could also be the pressure differential switch. Try disconnecting that and then pushing pedal.
These are just guesses though. Good luck.

I just completed another brake pressure bleed on Saturday, no air in the system. The two lights now only come on when the pedal is pressed all the way down regardless of the engine running or not. I replaced the fluid level switch before, (was my first thought). I tested the old switch by connecting two of the terminals together, causing the lights to turn off, which should'nt have. There was several parts that failed at the same time, so I replaced everthing except the booster and two switches. The problem might be caused by the vacuum-assist power booster, (the last thing I thought of). There is only very slight pressure coming out of the check valve (less than 10psi, my guess), when the brakes are applied. I just noticed on Monday that the pedal no longer becomes stiff, when the brakes are applied with the engine off. There is only one possiblity I know of, a vacuum leak. I checked the push rod using a gage and it's set correctly. Luckly the vacuum-assist booster unit is cheap. I'm going to try and replace this unit and rebleed the system. Once I can pick up a pressure/vacuum tester, I'll check the pressure in the brake lines. It's possible one of the parts I replaced might be bad from the dealer. We'll see. I'll post a short message once I have the new booster installed and tested, to let everyone know if the RABS system is working or not.

Well the power booster did not fix the problem, but it did help. I was able to finely get the error code. I got a code 4 (Grounded or closed RABS or RWAL valve switch). This is part of the electric hydraulic brake proportioning valve (a Kelsey-Hayes type). I check around for info about this part and found out there is a major problem (or defect) with this type of unit. Air and dirt tends to get trapped in the acumulator part of this unit and is hard, if not impossible to remove. I replaced this part last year, looks like I will have to replace it again if I can't flush the unit out. Has anyone tried using Alcohol to flush a brake system? I heard about using Alcohol instead of brake fluid to clean and flush out a brake system, but I don't know if it's pure alcohol or deluted with water. I'm thinking of replaceing some brake lines and doing a complete clean/flush.

***UPDATE***
I found a place where I purchased a copy of the shop manual for my truck (not the kind you can buy at a store). Following the trouble-shooting procedures, I found the problem. ABS error code 4 is usually an indication of an open or short somewhere in the 535 circuit. I replaced the modulator valve (again) and cleaned the connector. Pin 6 on the RABS computer module is a common problem, but not this time. There is a technical service bulletin on that issue. Corrosion was to blame on the connector (still need to replace). Because of the signal coming from the ABS computer module to the valve to activate the solenoids had too much resistance trying to get through the corrosion. I replace the valve as a precautionary measure. Since debris can destroy the valve, I took no chances. I flushed the entire brake system out using pure isopropyl alcohol. It seems the alcohol did not damage any of the seals. Then I pressure bled the brake system using 20psi instead of 15. I found out the max pressure is 30psi. I'm in the process of getting used to not seeing the two "idiot lights" come on. The brake pedal is very sensitive now and firm. Before there was little resistance in pressing the pedal. One less problem to worry about.
By the way, ABS systems need to be flushed at least twice a year. If there is a lot of debris in the system, alcohol is used. Otherwise, flushing with new clean brake fluid is recommended. Don't try to use DOT 5 brake fluid in an ABS system, seals won't hold for long (I heard about it). For everyone who gave me advise in solving this problem, Thank you. Your advise helped me to take another look at the parts that I already replaced once before, even new parts can be bad out of stock.

I have a 1997 Ranger 4.0 6 cylinder automatic transmission with 211,000 miles never had any problems except I had the transmission overhauled yesterday. the A/B light started blinking and the transmission started acting up, slamming into gears. was told that the A/B blinking indicated transmission problems, will cause overheating damageing other parts, will not show on temperature guage, My ABS light came on over 100,000 miles ago. I was told to ignore it, it is a common problem, I don't know if this is true, but my brakes have worked fine, had pads replaced 40,000 miles ago , still working fine.