2001 Ranger XLT 4x4 has had an ABS light on for some time. Took it to the brake shop and they said their ABS code reader cannot communicate with my trucks computer and they feel the computer might be bad. What are the signs of a bad computer?

I also have a DPFE sensor that goes out every year and that is extremely rare (from what I've heard) and also been told that is from a poss. computer issue. Replaced 5 of these things!

 

I've read through your other posts about your Rangers woes.

Do you have a CEL lit??? If so have the computer scanned for trouble codes & post All trouble code Numbers found. Most autoparts stores will do it at no cost if the CEL is lit, or your having problems. If their scanner won't work, check your cigar lighter fuse to see if it's removed, or is blown, as the scantool DLC also gets it's power through this fuse. Not sure where the brake shop was plugged in when they had their scan problem?

Are you replacing the DPFE sensor with an after market, or Motorcraft one???? Are you testing the DPFE sensor before replacement???? There are vacuum lines connected to the DPFE sensor, so are you certain they're in good condition & unplugged, as carbon, ect will tend to build up in them & on the EGR valve end there is a small orifice that can get plugged up with carbon & cause mischief.
Look in the "Tech Info" thread atop this forum for ideas on trouble shooting/testing your DPFE & EGR system components.

On the ABS light being on, are you having any other problems, like the speed-o acting out, auto tranny shift problems, cruise control acting out, if so suspect the rear differential mounted ABS speed sensor, as the ABS system & those other things also use it's PID output to the computer, to do their things, so if that speed sensors output is corrupt, they'll act out also & are good clues that it, it's wiring, or electrical connector should be high up on your suspect list.

Did you get the 09 damaged front wheel speed sensor replaced???? If so, are you certain both front wheel sensors & their electrical connectors & wires are still ok & the sensors are free of debris????

Let us know what you find.

 

My CEL is lit when the DPFE goes out. The trouble codes lead me to the EGR and then the DPFE.

The brake shop just stated their computer cannot communicate with my trucks computer??

I have disconnected the rear differential speed sensor and cleaned it, but I did not replace it. I will try replacing it.

ALSO, several years ago my cruise control went bad and it was some sort of wiring harness under the hood. AND, last april I had to have my tranny rebuit for $2,000 because my reverse went out (45,000 miles). Speedometer seems fine.

I have taken pipe cleaners to the DPFE vacuum lines and also my air compressor and blown them out and there is nothing in them. NOW, I can't reach all the way down and I don't know what or if the air blowing in is helping or not, but every 11 or 12 months the CEL comes on and when I replace the DPFE and reset the light, it is fine for the next 11 or 12 months and it happens all over again. Auto Zone thinks I have a corrupt computer also. They said if I disconnect my DPFE when the truck is running it should run rough and it doesn't...purrs like a kitten??

Haven't heard of the 09 damaged front wheel speed sensor?? What do you mean by that?? I haven't checked speed sensor debris yet.

Question for ya...When I disconnect my battery for a while and then restart my truck with the battery reconnected, the ABS light is immediately on. I have heard that it shouldn't come on until there is a problem sensed when braking. So it should be off after a battery reset until if sees a problem. With mine coming on immediately, does that tell you anything?

Truck has been a lemon and there is no question about that. I have fixed or replaced so much on this truck it's crazy. Thanks alot for your help!! Mike

 

On the front ABS wheel sensor problem, I got the idea from this 09 post of yours.
Ford Truck Enthusiasts Forums - View Single Post - ABS Engaging at Low Speeds (2001 4x4)

On the brake shop computer not working question, check the cigar lighter fuse, if it's blown, a scantool, or code reader won't work when trying to scan the vehicles engine control computer if thats what they were trying to do.

When you reconnect the battery & switch the ignition to KOEO, dash lights including the ABS lamp will light up, while the computer checks the systems & then if no problem they'll time out & turn off, Unless there is a problem, so if your ABS light is remaining on after the engine is running, the computer believes it has detected a problem. So begin by checking the usual things like the brake master cyl fluid level, wiring to the ABS motor, located on the drivers side inner wheel fender, front & rear speed sensors, their electrical connections & wiring or fuses, if all that checks out, or if the brake shop was trying to access the ABS electronic module/computer, suspect it.

On the CEL, post the trouble code Number/s your pulling, as they can offer up good trouble shooting clues.

Seems to me if the drive train computer is having a problem, it wouldn't heal itself with a new DPFE sensor, so it would seem to me that something else is in play here. Again, are you using an aftermarket DPFE sensor, or a Ford/Motorcraft part?????

Have you pulled the EGR valve & checked, or cleaned the orifice below it, to make sure carbon isn't plugging it, as that'll corrupt the feedback to the DPFE sensor & it's electrical output reading to the computer. Check all the vacuum lines in the system for dryrot, loose fitting connections & check the vacuum switching valve & the VRef voltage to the DPFE sensor & vacuum switching valve. Look at their electrical connector for bent pins spread sockets, or corrosion.

Let us know what you find.

 

My 2 cents.
Grounding issues will cause all kinds of drive you crazy, problems. Including trashing you computer system and giving false reading.Which in themselfs can cause safty issues. You may want to check your ground strap between the frame and the body. Also, check that the comp is making good contact with the body and so on. Bad grounds burn up a lot of small items to start out and work up to even bigger items down the road. Also, on sensors, never, and I mean NEVER, buy after market. ALWAYS use origanal parts. It will save you a lot of heart ache, time, and money in the end. Just thought I would through that out there. Best of luck to ya.

 

Thanks guys for your input. I have always used an aftermarket DPFE sensor. I always thought if the Motorcraft part failed so early in the first place, why should I replace with the same thing?

I don't hae the CEL code at this time because every year when it comes on, I know what the problem is and I fix it. Last time I had it read was probably 3 years ago. I don't remember the number but I do know it read "EGR Insufficient flow".

Have not pulled the EGR to clean below it. Heard that wasn't easy to do?? I am pretty mechanically inclined and will give it a try.

Will also check the grounding points. Thanks again and anything else, please feel free to throw it at me. Mike

 

Look here for a pictorial of the EGR system & note where the two hoses from the DPFE sensor connect on the pipe below the EGR valve, between the orifice. Thats the orifice you want to make sure to clean. You have to remove the valve & look in to see it.
Ford EGR/DPFE System

If the engine is using oil, the orifice will more likely have some carbon around it.

If your using AutoZone DPFE sensors, that may be the under laying cause of so many failures & your right, a yearly failure isn't normal, even for an OEM DPFE sensor. My 94 Taurus & 99 Rangers DPFE are OEM, so far never been replaced.

 

Great Picture of EGR system, thanks. I will dig in and see what I can find. Any tips on how to clean it or what to use?

Engine does not burn oil at all.

Auto zone scratches their heads when I walk in every year. The DPFE sensor has 2 yr warranty so they just hand me a new one every year.

What do you think about my truck idleing fine with the DPFE disconnected?

 

Sounds like it was a P0401 code, thats for insufficient EGR & is usually associated with the DPFE sensor, but could be caused by leaking vacuum lines to the VSV which under computer command (from the feedback the computer gets from the DPFE sensor) has the vacuum switching valve send vacuum pulses to the EGR valves diaphragm to have it open & feed some exhaust gas back into the engines intake manafold. Sorta like having the engine eat some of it's own "stuff" if you will.

SO, if any of the EGR systems vacuum lines, switching valves, diaphragms, or feedabck orifices are leaking vacuum or plugged, or otherwise corrupted, the system can act out & set a P0401 code, thus you can see a number of things can cause mischief.

From our "Tech Info" thread is a link on how to test the DPFE sensor.
http://rockledge.home.comcast.net/~r...tage-Test.html Read through the remainder of this 5 page thread for more info.

If the feedback orifice & the DPFE sensor check out, have a look at the VSV to see if it's diaphragm will hold vacuum, the vacuum lines to it are ok & that it's Vref voltage checks out ok.

Does the AZ DPFE sensor your using have a metal, or plastic body????

Keep looking & you'll likely find the culprit. Let us know how it goes.

 

P0401 sounds familiar.

My DPFE is plastic..all of them have been plastic. Even original. This is great information and I seriously appreciate your time. I would love to fix this problem once and for all.

What is a vacuum pump and how do I use it and get one? Also, how do you check voltage on the DPFE when it is plugged in? I can't get to the terminals?

Also, can you tell me how to properly clean out the lines from the dpfe to the exhaust? Thanks again.

 

Read all of the threads whos page links I posted for other how-to suggestions.

Depending on the deposit types you find in the EGR valve feedback orifice, maybe try a pipe cleaner & or piece of copper wire, so you don't open up or otherwise damage the orifice diameter.

You can find a hand vacuum pump at Harbor Feight, or rig one with a hand soap pump.
It's syphon tube will pull a pretty good vacuum & you could "T" in a fitting to your vacuum gauge & sorta fashion a tester.

Back probe wires where they go into the electrical connector. If your test probes are too large in daimeter, fashion a probe from something like a flat hair pin & slip it in so that it contacts the pin or socket the wire is connected to.

OK, so you've been getting the newer design plastic body DPFE sensor.

Pull the DPFE sensors electrical connector & check it's pins & sockets for corrosion, or bent pins/sockets.

 

OK, will do all of this tomorrow. Thanks once again!

 

my 99 ranger abs light was on to and the breaks were not working right replaced both abs cables in front now the light is off

 

I have had the same problem with the dpfe sensors on a couple of the 98 rangers at work. Now don't freak out, but when you pull the 2 hoses off did you notice any moisture in the hoses? One truck had a cracked left side head that was pushing just enough coolant out of it to be sucked into the egr tube then into the dpfe sensor. This in turn shorted out the sensor. The other was a loose wire inside the electrical conector. I hope this isn't your problem. But is something else to look for when the sensor goes out next time. As for the ABS light have you checked all of the fuses? Sometimes the simplest things are the hardest. Good luck.