spunbearing

Ok the rain finally stopped and I need to figure out what is wrong with my ABS. How do you test the RWAL sensor? I looked it up in the computer at my friends shop and it says to short out the black wire on the module and it will give trouble codes. I couldn't find a black wire on the harness. Am I looking in the wrong place? Maybe I had the wrong module. Is it the module behind the glove box? I don't want to just shorting wires until I know for sure that I have the right one. Any help would be appreciated.

Den

There is a single wire plug on hidden behind the glove box. With the key on, jumper this wire to ground for about 2 seconds.

If the anti-lock light is always on, it will show the fault code if momentarily grounded.
Count flashes for fault code


1- Not used
2-Open isolation valve wiring or bad control module
3-Open dump valve wiring or bad control module
4-Closed RWAL valve switch
5-Over 16 dump pulses generated in 2wd vehicles(disabled for 4wd)
6-Erratic speed sensor reading while rolling
7-Electronic control module fuse pellet open, isolation output missing, or valve wiring shorted to ground
8-Dump output missing or valve wiring shorted to ground
9-Speed sensor wiring/resistance(usually high reading)
10-Sensor wiring/resistance ( usually low reading)
11-Brake switch always on. RWAL light comes on when speed exceeds 40 mph
12-Not used
13-Electronic control module phase loop failure
14-Electronic control module program check failure
15-Electronic control module RAM failure


I would unplug the module behind the glove box ( straight inside) before worrying about trouble shooting. Mine acted up one time and that was the fix...needed to be reset. Disconnect for 5 seconds.


Den

spunbearing

Thanks for the reply! That's exactly what I was looking for. I haven't had a chance to work on it yet because the 2+ weeks of rain put me way behind at work. Now it's raining again. I give up! The wire you are talking about is it black? Thanks again. As soon as I can take the truck out of service for a day I'll check it out.

wannadiesel

Dragging this one up from the depths to clarify some info and add a pic. The RWAL diagnostic connector is hiding behind the glovebox, not over by the hood release. Thanks to flashgordon for the pic. The flashlight handle is pointing at the connector.

loch

Then whats the plug by the hood release on a 89 ?

wannadiesel

That should be the "rolls" connector. It's a feed off the rear axle sensor that was used for factory final testing.

flashgordon

Hmm, so do you mean that i could have used that to see if the arwal sener was working or sending a signal to the computer!

wannadiesel

All that would tell you is that the sensor works. It would have a low AC voltage when the truck is moving.

flashgordon

Most of the time that there is a anti-lock light on, it is usually the wire going from the frame to the rear axle, is broken or highly resistaned. this wire is moving every time the truck is moving and fatigue will aventually brake the wire....evan tho you may not be able to see it visualy!

the sensor in the rear diff, will usually out live the rear wire 2to l.
if the code is#9 it is allmost gauranteed to be the wire off of the frame to rear diff then, the sensor or a broken wire any were's els!
The wire is still avallabe from chry, but if the conectors are good and your good with a soldering gun...then cut and splice and your done. other wise it will caust you a little over a $100.00 for the replacement wire
there is many thing that could put the light on but this is the most common! just my .02

Ace

I was gonna start the new thread "RWAL Woes Part III" but this one does not seem to be finished - and I have the RWAL woes now too! Some new clues and info to work with now:

I think I actually engaged the RWAL the other day, when a tractor trailer swung wide turning into my lane and causing me to mash the brake peadal enough to engage something that did not feel too good in terms of stopping. Had to be the RWAL back there. Next day (that would have been Thursday) guess what? Brake warning and Anti-Lock dash light stays on.

So I went back and did a search that came up with this and other threads, but no joy. That plug behind the glove box has no connection to it and it is not clear to me what it does or what how to use it. How do I get the code out of it? Checked the sensors on the diff, brake valve and could not find anyting under the booster. No apparent vacuum leaks. Brakes seem fine, except I hate that feeling in the pit of my stomach when the RWAL egages!

I'm pretty sure that one event when I slammed on the brakes was what instigated the warning light, but why? how?

flashgordon

My guess is that the rwal work but the dump valve didn't re-center....maybe a nether panic stop to re-center the valve!
the taped conector need's to be shorted or a jumper from one terminal to the eather and then for a couple of seconds.
the light on the dash will start blinking it code....... check the code chart posted previously and that will get you started!
If the code in 9 then remove the wire form the rear diff and the eather end next or on top of the frame.
us a volt meter and check the resistance of the wire. if it's hi or open you have fould your probem........I don't thing this is going to be the code that you fined tho

comptz

I have found the wire you guys have been talking about and the code i have right now is code number 4. Can anyone give me a little more information on this? i don't feel like spending $175 for a new hydrulic control valve if thats not the problem. Any help will be appreciated.

HappyCamper

PM sent.

wannadiesel

Unless there's a problem in the harness, it's a bad dump valve.

comptz

where would that be?