Elecrical / sensor problem? Need suggestions please..

[99Lightning]

Hello all-

Just purchased a very nice condition 99 SHO (to go with my 99 Lightning). Car has 102,000 miles, and seems to run very good, shift fine, etc.

I am noticing that that every once when I drive the car (actually every trip)that the O D off light starts flashing, and the odometer and speedometer quit working as well. As soon as I shut off the car and back on - things are back to normal.

I also noticed that just this morning the the abs light was coming on/off prior to this happening on my way to work.

One more puzzling thing... The cruise control did not work when I bought the car. Just for the heck of it, I tried it this morning, and it worked (light came on too) for about 2-secs, and then right back off (with the O D light flashing and speedo/odo not working again. It almost seemed like this triggered it, but cannot be certain.

I also noticed that one time this past weekend going down the highway right before this hapenned, that the engine seemed to cut-out (and instantly right back on) before the flashing light/speedo problem started.

Not sure where to start (VSS sensor? - if there is one, take it to a dealership, etc). Sorry for the long post, and any suggestions would be greatly appreciated.

Thanks.

 

[SHOZ123]

Check the battery voltage when it is running. Must be above 13.5V with a full load.

 

[99Lightning]

Check the battery voltage when it is running. Must be above 13.5V with a full load.

Checked out at 14.2V at running idle with lights & blower motor on.

 

[SHOZ123]

I would next pull the instrument cluster out and check the connections back there. Pretty easy to remove. Two screws hold the the black surround in, then 4 screws hold the cluster in.

 

[rubydist]

First, put a code reader on the car and see what codes are stored. That will save you a lot of guessing and wasting money on "maybe this will fix it".

 

[99Lightning]

Thanks for the input. Yes, I think I'm going to have to take this in to get it looked at.

I noticed on my drive home yesterday that this happened again as I was getting on the highway. One thing for sure, is that the car would not downshift under full throttle (while the OD light off was flashing - with speedo and odo not working too). I manually shifted out of OD to drive fine, even tried to put it in neutral and back to OD. I finally put the vehicle in neutral (at 70mph), shut it off, started it right back up, and then it was fine. Everything worked again - would downshift under heavy acceleration too.

I also noticed for the first time after I got home and checked the tranny fluid (in idle) that the fluid level seemed way too high - like twice as far up the dipstick as the full mark.

Whatever the problem I find, I'm beginning to think this isnt going to be a cheap/easy fix....

 

[bacernate]

Sounds like a classic abs module failure. The vehicle uses abs module input for the speedo, no vss. Could also be an ignition switch failure, never seen it on a ford yet but sounds like a classic gm ignition switch failure. But I would for sure get the codes pulled out of the pcm and abs for sure. If it won't communicate with the abs module it's likely doa.