94 Ranger ABS and brake light on

[94Rang4.0]

Hey All, been a long time viewer of this forum but never made a post but this issue I'm having is making me insane.

ABS light is on and brake is on dim. I've tested and replaced alot of components in my quest to figure out this issue as I've found issue along the way.

Here is what I've done:

-New RABS valve(leaking from blessed)
-New master cylinder (signs of leakage and snap ring half missing but somehow still locked in)
-New booster(leak internally)
-New front calipers and hoses
-New bleeders rear

I've bled and bled and bled thinking RABS still has air in it(waiting on a vacuum bleeder to try more bleeding)

I didn't try to bleed from RABS bleeder because of mixed opinions I saw on forums about needing to do this. I did however bleed it with a short brake line attached to the output side of the RABS before attaching the line that goes to the rear.

I pulled abs codes prior to all this work and got code 4. Open or ground dump valve. I have gone through the steps to diagnose short/ground etc. But I'm stuck on 4.7 and 4.8. are these tests supposed to be done with abs and rabs connectors installed and back prob rabs connector. If left unplugged my readings are high. All plugged in and back probing I get 10k ohms on pin 2 and valve body on rabs. Good. 4.8 is to check ohms from pin 2 to pin 3 on rabs. With installed and back probing I get 10k ohms but range is supposed to be 18-26 k ohms. Could this be a corroded connector? I have another junkyard abs module and I get the same readings. What is chances I have 2 abs modules with same problem?

Other than checking and cleaning connections for the 100th time and maybe bleeding again, I don't know what else to do. Maybe buy a "new" abs module?

Please any help on this would be awesome. And I will definitely follow up with solution if it's ever figured out

 

[RobbieD]

With the red brake light on dim, look real close at the connector on the base of the brake fluid reservoir and make that it's not corroded or the wires are frayed (had this issue on one of mine). Also try unplugging the wire at the parking brake switch and see if the dim brake light goes away (clean or replace this switch if it does go away).

The RABS system is tied into the red light's fluid warning and parking brake wiring, and that circuit must be operating correctly in order to diagnose the RABS. Your "brake is on dim" symptom indicates a problem in that system; if you can resolve that, then see what the RABS does.

 

[94Rang4.0]

I completely agree. Which is what alot of my testing was. The red light does get brighter when pushing down on the float in master and also gets brighter when applying the parking brake, so I believe I can rule those out. The red brake light does go out when disconnecting connector from float switch though. Also, red brake light and abs light goes out when you disconnect the abs module. I think the abs module is what is turning on the abs light and dim brake light. I also tested the brake warning diode and resistor (disconnected cab harness and pcm harness to isolate and test) all good. My ideas are this:

-Bad abs module
-Air in dump valve causing low ohm reading
-Bad "new" RABS valve

 

[RobbieD]

Your testing seems to me to have been pretty good to this point. What reference material are using for the testing?

 

[94Rang4.0]

I've gotten some good sources for code 4 troubleshooting guides. Here is what I've been using:

https://www.ford-trucks.com/forums/664920-getting-abs-error-code-4-a.html

https://www.justanswer.com/ford/0kqq4-trouble-code-flashes-times-brake-light-on.html

 

[RobbieD]

If you'd like, tomorrow morning I can post the Ranger RABS troubleshooting steps from the '94 Ford shop manual. It's about 10 pages.

 

[94Rang4.0]

That would be great! Please. I appreciate it

 

[RobbieD]

You got it; tune in tomorrow, same channel.

 

[RobbieD]

94Rang4.0- I forgot to say "welcome" to TRS.

OK, honestly I think it's best if you start fresh on the diagnostics, especially after reviewing these first pages. This is from the Ford 1994 shop manual, so it's going to be the most accurate, in my opinion. What you're working from may, or may not, be correct for your model year.

That dim red brake light is bugging me. See the second page I've posted, where I've highlighted.

And if your truck is a '94, it should have RABS II. This is the troubleshooting flow chart:

The best next step, is review all of this, ensure the RABS is working correctly enough for diagnosis, and then get to where you can get the diagnostic code(s). From that I can give you the correct pinpoint testing pages that specific code, as the entire manual RABS section is 64 pages.

Last page this post, is a wiring diagram (in case you don't have one, or don't have the correct one).

Just let me know, what sections will help next.

Good luck!

 

[94Rang4.0]

Hmmm. Your right about the dim brake light. It makes me wonder if something else is going on. I'm going to dive further into the brake light a bit. Thanks so much for this! It will definitely help. I'll keep you posted

 

[RobbieD]

Good luck. Let me know what manual pages will help you next. You can "Reply" to my post, or PM me, so that I'll see a notification.

 

[94Rang4.0]

Good luck. Let me know what manual pages will help you next. You can "Reply" to my post, or PM me, so that I'll see a notification.

I did some more testing and everything just led me to believe the new RABS valve I installed was the issue. I changed it again and bingo no light! I should of never put so much faith in a "new" part. Thanks again for all the help.

 

[RobbieD]

Good to hear, and glad that you resolved the issue. New parts quality sucks these days, and thanks for posting how it turned out.