1st Gen Ram Tech'93 & older Rams: This section is for TECHNICAL discussions only, that involve 1993 Rams and older. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
Today I saw my brake warning lights come on when I start the truck and they don't go out. Both the brake light and the anti-lock warning light. I did a quick google search and noticed some people taking about this problem being caused by a bad "speed sensor". Another symptom is the speedo gauge doesn't work at real low speeds. And in my opinion my speedo has this problem.
I don't know if 1990 trucks have this problem though or if it was only something newer trucks have (this speed sensor thing).
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The RAWL (Rear Wheel Anti Lock) brake sensor is in the rear differential and has nothing to do with the speedometer. The RWAL microprocessor will store and display one code at a time when the light is on. The code (1-15) can be read by the number of flashes on the RAWL light when the RWAL diagnostic connecter is grounded. The diagnostic wire is a black 18 gauge wire that comes off pin #5 of the electronic brake control module.
I have noticed the same thing on my 2000 Durango. The 2 lights (anti-lock and E-Brake) are lit and the speed-o does not register anything below 20mph. I took the truck back to the guy we got it from and he said that the 2 problems may not be related. I think they are. So, if the problem is a bad speed sensor, how easy of a fix might that be?
The E-brake has nothing to do with the antilock system or its speed sensor. If the parking brake light is on it is either a bad or miss adjusted switch which is on the parking brake peddle. This switch only monitors the position of the peddle and not the brake itself.
Or you can google your vehicle and year and "speed sensor" and abs warning light.
My problem is all the info on that subject seems to be related to newer dodge vehicles. I don't know if any of it relates to pre-93 vehicles.
My mechanic told me the reason my warning lights are on is because something is wrong with the abs system but he didn't think the truck itself is worth putting the money into looking into what the issue is exactly.
Anyway, for your vehicle if it is a speed sensor problem, everything I've read about it says that it is a cheap and easy fix to do.