vacuum cruise control inop., int. rabs light

[OkieTruckerD]

I was driving along the interstate one day, using my cruise control, and out of nowhere, my truck started bucking, and the cruise kicked out, I tried re-engaging it, and it wouldn't come back on. At the time, I had a matching set of 265/75R16 on it. Now, I have 285/75R16 drive tires on it, and 265's up front, and that's where the RABS light comes into play. What can I do to fix the cruise? Can I change the speedo gear, and if so, which one? If I left any info out, please let me know. BTW, I apologize for being gone for so long, it's good to be back on oilburners!

 

[Agnem]

The RABS light (and system) has no effect on vacuum cruise. It's been disabled on the Moosestang for years and the cruise works fine. The speedometer however is critical. There is a good diagnostic procedure in the manual on how to find out whats wrong.

 

[OkieTruckerD]

What manual do you refer to?

 

[OLDBULL8]

Possibly the first thing to do is check for vacuum, the vacumm reservoir can on the drivers side is important for cruise control. With a vacuum gauge, you should maintain around 21HG of vacuum.The clutch switch would be next to check, you can jumper it out and see if that is defective. Check your brake taillight lamps, sometimes they will short out causeing the CC to disengage. I have the whole diagrams for the 89 if you need them. PM me for them.

Edit: If your AC and Heater controls work OK, your vacuum should be OK.

 

[OLDBULL8]

To address the your problem with the RABS unit, get the flash out codes then list them here. Locate the RABS diagnostic connector with the black/orange wire and attach a jumper wire to it, momemtarily ground it, them the RABS light should start flashing, it's located behind drivers side kick board. The code consist of a number of short flashes and ends with a long flash. Example: three short flashes and ends with a long flash, that is code 4. This is done with the Key ON Engine Off. I don't think tire size has anything to do with the RABS unit malfunction, you only have rear wheel RABS.

 

[OLDBULL8]

BUMP Hope dieselman21585 see's his post again.

 

[OkieTruckerD]

Thanks Old bull, and Agnem. I will when I get home. Btw, my heater controls work fine, my truck doesn't have a/c, yet.

 

[jaluhn83]

The bucking makes me think there's a problem with either the speed sensor or the actual computer. Clean all the connections first of all.

The factory manual and factory troubleshooting manual have some good info. I'll see if I can scan that for you.