90firstgen

My speedo started messin up the other day. Sometimes it doesn't work at all and sometimes it just bounces around everywhere between 0 and 100 mph. And sometimes it works perfectly. I've checked everything on the tranny as far as tightness and everything is plugged in. Any ideas? Should I just buy the sender and see if that fixes it? Has anybody else ever had this problem?
Thanks

6Lpowerstroke

is it the cable style?

if it is the square end could be rounding or stuck too far in. i had that problem with my truck and i had to shim it to get the end back where it belonged. hope this helps

goodtyms

If your truck has the VSS (Vehicle Speed Sensor) like my '93, instead of a cable drive, then that's likley the problem. When it finally fails, it won't allow overdrive tranmissions to shift into O/D.

Caincando1

My 90 does the same thing when it's wet out. Usually when it's a wet snow, never does it when it dry or just a little wet out. After I've driven it for a while and whatever is wrong dries out it stops, unless the roads really wet then it will continue. When you figure it out, will you let me know, so I can fix mine...

old dog

1992 350 dulie auto 2w
Its your speed senser just replaced mine after 2 yrs of hell trying to figure out what was wrong, OD will drop out on you your speedomoter will jump all 0ver then smoth out so you think its correct<WRONG < i THINK IT COST ME $36.00 AT ACTION AUTO,IT TOOK 5 MIN IN THEIR PARKING LOT AND IT WAS ALL FIXED. do it NOW AND SAVE YOURSELF A LOT OF PROBLEMS , AND HEADACHES.
CLAUDE

keithplacervill

mine became round so being a sparky i took some electric tape put it around the shaft and jamb it in good as new and freeeeee

BearKiller

Correct me if I am wrong; but, the 90 model with Getrag should be cable driven.

My guess is that the cable is binding in the cable housing, winding up, then springing loose.

This will make the speedometer quit, then bounce way high, then work fine, etc., etc.

If you let it go long enough, it will destroy the speedometer gauge.

Caincando1

I guess I should clarify that mine does not jump past the current speed. I will just stay at zero or jump in between dead zero and the current speed.

My problem does sound a little differnt than 90firstgen's.

90firstgen

Ok, I'll check the cable and see if its binding. Thanks a bundle

BearKiller

To check the cable, unscrew it at the adapter(transmission end), and chuck a drill to the end of the cable.

Put the drill in reverse(un-drill) and, with someone in the cab watching, slowly apply the drill; it won't have to turn very fast.

Slowly fluctuate speeds through several cycles and observe how steady the needle is.

Speedometer problems are not easy to diagnose.

gerry

If you pull the cable off at the back of the speedometer you can pull the cable out og the housing... Use some white lithium grease on it as you shove it back in. Also check for any loose strands on the cable that may be binding up the cable.

Bill Tomlinson

I sure hope that you do NOT have the same problem I had when my speedo started getting creative. I had snapped off the end of the output shaft of my getrag.

HappyCamper

I am ressurecting this thread in hopes to get all ideas including any new ones. My speedo has been exhibiting the jumping off and on for a few years.

The truck is a manual (Getrag 360), year is early 91 (non-intercooled). The speedo acted up on out trip to Yellowstone this past weekend (abt 400mi. one way). On the way home the speedo started fluctuating between 0 and the actual speed.

From earlier posts I gathered

1. Check the cable for binding. 2. Check the cable end where it plugs into the trans for rounded corners etc.

Any input is appreciated...

Thanks!

imabnormal

mine was doing something similar, although mine is electronic, not cable driven. the nut that held it into the trans had loosened up and i'm figuring that the input to the gear box was barely making contact and therefore only working most of the time.

i'm sure that after messing with yours as much as you have you would have noticed it being loose, but did you also confirm that it goes into the trans and the speedo far enough to engage both units?

HappyCamper

Thanks imabnormal,

I will be checking that this week. My truck is used mostly weekends for general puttering and also for trips - so I will look at it tomorrow evening after work. I will check the nuts, bolts, etc. for tightness.

Rich