I know there have been a few posts about this topic with the common complaint of the Brake and ABS warning lights both staying on. The consensus is to ground the RWAL control module and count the flashes to determine the problem. My trouble is with the actual grounding, it simply is not working. So, does this mean the RWAL control module is totally shot? Just a bad diagnostic connector? People have mentioned that when this happens the speedometer or odometer will cut out. My odometer hasn't worked for a while and my speedometer works about 80% of the time. Is there a way to test the control module or rear speed sensor with a voltmeter? I want to avoid buying unnecessary, expensive parts. Thanks!

Its a 91 D150 with a 318/A998 setup.

 

i just disconnected the abs control module on my truck. it is behind the glove box.

 

I was wondering if there was a way to test the few I have found in salvage yards.

 

you can unplug the sensor on the rear axle check the 2 wires one should be a ground and one should be 5 volts i think then you can check the resistance across the sensor i think spec is 1600 - 2300 ohms if more or less then the sensor is bad usually you wont get any ready because they are completely dead, usually what happens is the sensor goes bad ,the 2 lights come on (ABS & Parking Brake), speedo doesn't work till a certain speed (ex: starts working at 40 mph) , and the cruise wont work right ive replaced alot of these, i haven't replaced a module yet

 

So I have a '91 D250 cummins with an auto trans. I am having issues with my ABS and Brake lights coming on. I've grounded the wire and counted the lights to a code 9 (Speed sensor wiring/resistance - usually high reading). After being directed to test the speed sensor I noticed the contacts were so highly corroded it broke off when unplugging.

After an install of a new speed sensor and pigtail socket, I reconnected my battery and 30 seconds later... ABS and Brake lights come on!?!? (still with a code 9)

Now while I have a multimeter and a test light, I'm the kind of guy that scratches his head when it comes to electrical issues... please, talk to me like a dummy if need be...

A resource online said to run a cable from the battery terminals(keeping them apart of course) all the way to the rear axle and test the speed sensor connections with a test light. The battery positive side lights when I connect to one wire. When I connect battery ground to the other speed sensor wire, nothing...?

Am I testing this right? Assuming the new sensor and pigtail work properly, how do I test the wires to assure there is no break/short between speed sensor and RWAL computer module?