Lazy Speedometer

Shadetree930 · 07-13-2002, 11:37 AM

Had the car out last night (87 Targa). Everything worked perfectly.

Took it out on errands this morning and noticed the speedometer and odometer were not working. Made a few stops, turned car off and on a couple times, and next thing I know, the speedometer and odometer are working again.

Any ideas what was going on?

Shadetree930 · 07-13-2002, 04:59 PM

bump

TR89-911 · 07-13-2002, 06:35 PM

I had that exact problem in April 2001 on my 89 - 911. It went off and on before it finally quit on me. The problem was the magnetic impulse sensor for the speedometer. It was an easy fix at my mechanic, and a fairly reasonably priced part.

I have no idea if it is something you could fix yourself. I do not do any work on my car.

MarkY · MarkY's Garage

Prials, do a search on speedometer on this forum. There was a thread on this very subject about a week ago. My recollection is that it has something to do with a sensor that can be accessed behind the front seats. Supposedly a pretty simple and inexpensive fix.

My speedometer did this in my 88 Carrera a couple of times about a year ago. It hasn't happened since and I didn't do anything to correct the problem... other that sweet talk my car.

I found the thread for you.

Speedometer fix

Early_S_Man · 07-13-2002, 07:32 PM

It could be as simple as a loose or corroded connection at the connection to the body wiring harness from the sensor. Or, it could be an internal fractured spot-weld inside the magnetic reed capsule ... that is making intermittent contact and has to be vibrated and heated a bit before starting to work in the morning!

Shadetree930 · 07-14-2002, 06:55 AM

Thanks for the help guys.

The car is going in for its 60k next week so I will have them replace the sensor while its in.

jluetjen · jluetjen's Garage

While we're talking about Speedometers, I've noticed a certain "personality" to mine. Admittedly it is an older model then the '87 that started this thread.

When I start from a dead stop, my speedo doesn't do anything until I reach about 30 MPH. After that it reads fine. If I slow down below 30 MPH, the speedo works fine unless I come to a dead stop. So it seems to be a bit "sticky" at 0 MPH.

Any ideas?

724doorE · 07-15-2002, 06:56 AM

John, isn't it neat how the needle rests on the peg at what ought to be about ten mph when not moving. That low speed stuff isn't important anyway!

See they never had pit lane speed limits back then

Mine works fine, through a wreck (well, being parked on the drivers door), broken gauge face glass, and a gauge bent bezel. But then there are always other issues

jluetjen · jluetjen's Garage

Oh! You mean it's not a bug but a FEATURE!!!!

Early_S_Man · 07-15-2002, 07:47 AM

John,

That quirky behavior can also be the result of a broken cable! when broken and frayed cable ends lose contact, speedo needle stays or drops back to the peg ... and when the ends 'snag' again, speedo needle jumps back to speed! At 0-30 mph speed range ... it is most noticeable!