Speedo's on crack - Diesel Forum

edex2 · 04-30-2005, 09:31 PM

sometimes it works. sometimes it doesn't. sometimes is pegs like a tach. sometimes the 'service engine soon' lite comes on. sometimes it doesn't. sometimes the override 'Off' switch blinks. sometimes it doesn't. sometimes the ABS light stays on, sometimes it doesn't.

I can't be the only one who has had this! What's up?

Bruce1954 · 04-30-2005, 10:15 PM

Grounds not connected would be my thought/

FMT what do you think?

rock_doctor · 04-30-2005, 11:29 PM

My vote would be a bad vehicle speed sensor in the rear axle. You need to read the code and see what it says.

mark

edex2 · 05-01-2005, 12:10 AM

First error code said bad vss. Second error code said internal error KAM. I will read it tomorrow. Maybe it will be different.

On the ground, are you thinking the main ground off the battery to the block or on the dashboard panel somewhere?

rock_doctor · 05-01-2005, 12:37 AM

There is a ground behind the dash that I think grounds the computer and dash electronics including the radio. Nevertheless, I would take the time to check both the dash and main chassis and engine grounds. If you go into the archived 7.3 power train forum, there were a few posts about the different ground issues and if I remember correctly, flaky gauge operation did turn out to be a grounding issue. If you can find the post, it probably will point you to the proper location of the grounds. Also, check the connections on the speed sensor I do remember some found the plug was corroding and periodically stopped working.

good luck,
mark

DR.billZ · 05-02-2005, 10:11 AM

Rear axle speed sensor. Easy to change.
Check out the older IDI engine Forums and you will see this is a common problem with them after a few miles. My old F-350's rear axle sensor went out at about 165,000 miles.

edex2 · 05-04-2005, 07:50 PM

replaced the vss. it was loose. work for about 5 miles. abs light is on now. override is blinking and the truck is in 'limp' mode. 2nd and 3rd gear only. diagonitics says the data going into the abs module from vss is good, but coming out of the abs module is bad. it will get a new abs module in the next couple of days and we will see what happens then.

edex2 · 05-06-2005, 09:48 PM

All fixed. Good as new. SCMT is reinstalled and we are towing again. Ended up being the vss and dirty connections on the abs control module. That is it.

Vindicator · 05-24-2005, 04:49 PM

Glad to hear ya got it repaired. There's nothin' like it whe you "fix" something and it actually works! LOL [img]/ubbthreads/images/graemlins/biggrin.gif[/img]