1999 Ford F-250 speedometer

DARRELLLANDRY

MEMBER
1999 FORD F-250
V8
2WD
AUTOMATIC
263,000 MILES

1999 7.3l powerstroke 3.73 rear end speedo work fairly well at low speeds under 50 mph an soft acceleration, over 50mph or hard acceleration needle drops to zero then back up to 30mph then drops back down then bobbles at 40 to 55 mph if you let off accelerator at highway speeds needle will jump up to 65 to 70 mph then drop below 30mph any help would be appreciated

7 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok it sounds like you may have either a speedo head problem or vehicle speed sensor or GEM module problem. So with that said do you have a digital multi meter and do you have access to a scan tool? If so get back to me and let me know what you want to do from here

SPONSORED LINKS

Was this

answer

helpful?

Yes

Monday, March 23rd, 2009 AT 3:05 PM

DARRELLLANDRY

MEMBER
4 POSTS

Ok I do have a digital muti meter no scan tool

Was this

answer

helpful?

Yes

Monday, March 23rd, 2009 AT 3:09 PM

RACEFAN966

MECHANIC
5,029 POSTS

OK first I do need to know if this is a F-250 or F-350 if it is a F-250 then is it a superduty or not? Get back to me with that and we will go from there. Now does this have cruise? If so then most of the tests for the VSS (vehicle speed sensor) will more then likely be done through the cruise circuit. Get back to me with the needed info.

Was this

answer

helpful?

Yes

-1

Tuesday, March 24th, 2009 AT 10:27 AM

DARRELLLANDRY

MEMBER
4 POSTS

1999 F250 SD supercab 7.3l disiel w, cruise

Was this

answer

helpful?

Yes

Tuesday, March 24th, 2009 AT 12:27 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok the VSS (vehicle speed sensor ) is on top of the rear differential. It should have 2 wires hooked to it. Unplug it and measure the resistance across the terminals of the sensor (not the wire harness) if it is not 900 to 1500 ohms then replace that sensor. Let me know what you find.