ABS OR RABS HELP
Thread Starter
|
New User
Joined: Jul 2013
Posts: 4
Likes: 0
ABS OR RABS HELP
Greetings, I am new to this site and need a lil help with my newly aquired 93 F-250. I have a solid ABS light only light on, and brakes seem to be a bit overly responsive. I'v done quite a few searches and figured out how to pull the RABS code from the module behind the glove box. I have a code 13, and from what I can find code 13 is a speed processor check but I've also seen under RABSII system that the code could be a faulty RABS module. I have already replaced the VSS in the differential and it didn't help, and I prefer not to throw any more money at it trying to fix the problem. I also noticed that my speedometer is a bit twitchy, but not sure if its related. Any help would be appreciated!
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
Try unpluggin the module and see if the brakes feel normal. Where are you referencing your codes from?
If the speedo is twitchy, it could be a bad VSS, PSOM, or RABS module. My 96 had the twitchy speedo, I checked the output from the VSS (good), checked the PSOM out and replaced it (suspected it was failing), disconnected the cruise control (it uses the PSOM signal), and finally the RABS module (also uses PSOM signal). Turns out the RABS module was screwing up the signal from the PSOM, which made the PSOM itself tweak out... and of course the EEC was reading this screwed up signal too so that's why my transmission was in failsafe mode.
If the speedo is twitchy, it could be a bad VSS, PSOM, or RABS module. My 96 had the twitchy speedo, I checked the output from the VSS (good), checked the PSOM out and replaced it (suspected it was failing), disconnected the cruise control (it uses the PSOM signal), and finally the RABS module (also uses PSOM signal). Turns out the RABS module was screwing up the signal from the PSOM, which made the PSOM itself tweak out... and of course the EEC was reading this screwed up signal too so that's why my transmission was in failsafe mode.
Thread Starter
|
New User
Joined: Jul 2013
Posts: 4
Likes: 0
I grounded the Orange and black wire coming from the RABS module under the glove box, I got 12 quick flashes, and then one long Flash(13). The PSOM, is that the actual whole dash cluster??, I pulled that, but wasn't really able to check the circuit board, being it was incased in plastic, perhaps I was looking at the wrong thing?? I'll try unhooking the module and see how it responds then, and see if the speedo still jumps.
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
The PSOM is the Programmable Speedometer/Odometer Module. It's the circuit board on the back of the speedometer face. This takes the raw signal from the VSS and converts it to a format that the PCM, RABS, cruise, and anti-skid modules can use. It also applies a calibration to the signal, so you can compensate for larger tires and such. When it goes bad (or is fed bad input signals, or when the RABS module goes **** up and shorts out the PSOM output signal), the speedo will bounce around and the auto transmission will go to failsafe mode, which is immediately noticeable due to hard shifts caused by the line pressure being maxed out.
You can take the cluster apart and remove the PSOM, and replace it with a junkyard one. If you're good with electronics, you can sometimes fix it. The only bad thing is that your mileage is stored on the PSOM, so if you swap it with one from another truck, then that truck's mileage is what'll be displayed on your odometer.
You can take the cluster apart and remove the PSOM, and replace it with a junkyard one. If you're good with electronics, you can sometimes fix it. The only bad thing is that your mileage is stored on the PSOM, so if you swap it with one from another truck, then that truck's mileage is what'll be displayed on your odometer.
Thread
Thread Starter
Forum
Replies
Last Post
TexasGuy001
1987 - 1996 F150 & Larger F-Series Trucks
32
Dec 1, 2010 04:31 PM
f150forever
1987 - 1996 F150 & Larger F-Series Trucks
8
Nov 9, 2010 11:32 AM
