speedometer not working
 

84 carrera 3.2.

my speedometer stopped working. what is the differential diagnosis? wheel speed sensor? motor speed sensor? speedo itself?

thanks for any input.

D

if your odometer isn't working, it's most likely your speed sensor on the transmission. I just replaced mine - it's also called the impulse sender. Check the parts catalog on Pelican - fairly easy to replace. If odometer is working, it mght be the speedometer itself. There are theads here to check continuity of the speedo sensor

Smell your speedo. If you get a burned smell, it is almost certainly the speedo. This is a common ailment. Mine cost a little over $100 and about a week to be repaired at Hollywood Speedo.

Any work done prior to failure?

Check the usual suspects, first the contacts behind the gauge, make sure they clean and tight. Second the connector in the tunnel at couple panel, make sure they are fully seated. Third the sensor itself at the side of gear box passenger side, remove and pass a magnet over it and ask helper to see if speedo moves/pulses.

Oh yeah, Welcome Aboard 3.2

Somewhere there's a post about testing. IIRC, you can make closed-loop pulses to test that the speedo side is working. --that should be step one.

Edit: although, that may not apply to your Carrera. --somewhere in the Carrera line the type of sensor changed to a hall effects.

Edit2 the 1984 uses the same sender as the SC Part #: 911-606-209-00-M100

Here ya go. http://forums.pelicanparts.com/porsche-911-technical-forum/868839-speedometer-help-needed.html#post8662058

Mine sometimes stops working, usualy after being stood over the winter, a tap on the glass while the car is moving usualy wakes it up, try it, it may just be that simple! :)
A.

thanks the info guys. I suspect its the speed sensor. the speedo and odo not working. will work from that angle.

D

Here are a couple more links. Good luck.
http://forums.pelicanparts.com/porsche-911-technical-forum/823075-speedometer-88-does-not-work.html
http://forums.pelicanparts.com/porsche-911-technical-forum/332604-smokey-speedo.html

Please keep us posted and break a leg and be safe while working under the car, wheel chocks and jack stands

84 911.

there was a blown fuse in the circuit. #4. replaced that - rest of instruments work on that circuit. Ive replaced the impulse sensor. no luck. only thing left is speedo, correct?

thanks

Dan

Did you flink the glass a few times while moving? ant7 has the right idea.

Mine did that before I sent it to get fixed.

oh and also read through the other threads. really good stuff and more importantly gives me a few other easy things to check. thanks all. will post up results of next steps.

dan

As shown in my edits above, you have the switch-pulse style sender. This means that it is easy to test the speedo.

Speedometer Sensor
 

This is a cross post with my RST build thread. As my issue is related to that of the OP, I thought it best to continue with this thread rather than starting a new one.
I'm almost there with my RST build but my speedometer does not work so can't pass safety test for licence sticker.
Read threads in this forum with no positive results.
Here is what I did.
Checked wiring into speedo ('86 based).
Speedo jumps immediately when the green and brown wires are touched together at the rear of the tunnel with ignition on.
Checked continuity of same wire connectors.
Disconnected wires at tunnel, put my digital ohm meter across the green and brown wires all while turning the right rear wheel. No movement in the reading.
Removed the sensor at the transaxle and ran a small magnet (the one on the end off the small extended handled mirror) across the sensor. No movement.
Did the same thing with the large magnet on the back of my magnetic parts tray, finally a 0.00 ohms reading.
Checked the seating onto the transaxle. All good.
So I'm wondering if the sensor is missing a piece on the sensor side. There are two arms that just stick out on the sensor side that appear to be to hold something that is not there. Also the inside of the sensor has a yellowish compound filling that looks unfinished. See pics

http://forums.pelicanparts.com/uploa...1467339540.jpg

http://forums.pelicanparts.com/uploa...1467339649.jpg

Any ideas?
Thanks in advance.
Cheers,
Johan

Is that a picture of the sensor? Looks more like the backup light switch.

It's the speedo sensor that resides on the right side of the transaxle. The backup switch resides at the front of the trani.
Johan

Hoping that someone will chime in with a suggestion.
Johan

Adding to this older post as I just went through this same issue today. After a complete engine rebuild in my '84 Carrera my speedometer was not working. I followed the advice of this thread and one other that was linked in this thread for testing the sensor. After unplugging the sensor in the tunnel, I placed a digital multimeter on each lead in the tunnel and selected the ohm tester with the beeper. While turning the right rear wheel (car in neutral), there were no beeps coming from the meter. I removed the sensor from the transmission and waved a magnet over it, the meter then beeped telling me that the sensor was probably good. I noticed the magnet triggered the beep on the meter easier and faster on what I thought was the back (outward facing) side of the sensor. For grins, I flipped the sensor over to what I thought was backwards. Now when spinning the right rear wheel, I got beeps as expected. I installed the sensor in this position connected everything up and speedometer works as it should. In short, the sensor was installed backwards. The correct way is the "sensor side" (capped finished look) against the transmission. The unfinished looking side with the "legs" faces outward.http://forums.pelicanparts.com/uploa...1583116630.jpg