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I have a 2004 PT GT turbo with 87000 miles. I was having intermittent problems with stalling and mechanic checked error codes and recommended I replace ECM. Just before ECM arrived, my speedometer stopped working. I replaced the ECM and things seem to be working fine, but the speedometer still is not working.

Can't seem to find any fuse that controls it, any ideas?
 

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Welcome to Allpar. What fault code was found? There is a transaxle speed sensor, but if it is an automatic and it's shifting OK then the sensor is probably OK.
There is no fuse.
Does the cluster pass the self-test?

http://www.youtube.com/watch?v=2mtmyl5VDFY
 

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Discussion Starter #3
This is a 5 speed manual. All other instruments are working, except the odometer is displaying but not changing.

Sorry, not sure what you mean by self test.

This happened after I had it in the shop so I haven't had the error codes checked yet.
 

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The 5-speed transaxle has a gear driven speed sensor at the differential. It may set a fault code if it fails. Does the odometer count up miles too or no?
The cluster self test is explained in the video. It will tell you if the cluster electronics have the ability to drive the speedometer pointer up and down the scale or not.
Fault codes may be displayed in the odometer window. Have a pen and paper handy and write them down.
If the speedometer still doesn't react with the self test, then you may have a failed cluster. Does 'thumping the dash top bring it back into operation at all? Does everything else electrically work?

1) Put the key in the ignition.
2) Hold down the trip odometer reset button.
3) While holding the trip button, turn the key to ON, and within 5 seconds the test should begin, and it will stop automatically when all the checks have completed.
 

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BTW, Thanks for the quick response! I will try the self test when I get off work, also the thump test. All other electronics seem to be OK. The odometer is not counting at all.

So much was happening with the ECM when this went out it is hard to sort out what exactly is going on. I have only driven 20 miles or so with the ECM replaced, so not 100% sure that is all straightened out, but it seems to be running smoother than it has in quite a while.

Thanks again for the help!
 

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Discussion Starter #6
Well I did the cluster self-check with the following results:

All gauges worked properly, including the speedometer.

It flashed the following codes:

FL00017
232138
EE 14
bL 01

I'm guessing that means something wrong in the transmission speed sensor area?
 

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Those numbers are probably software and module version numbers. Powertrain fault codes would start with a 'P'. Like a P0501:

http://www.obd-codes.com/p0501

Ok the speedometer is able to work, so we should look at the speed sensor and wiring. It is located at the passenger-side inner axle where it enters the differential. You may be able to get at it from up top if you move things out of the way.
Sometimes the pinion drive/driven gears would wear or break on these. Determine that by removing and inspecting the gear in the transaxle and the gear on the sensor first. Sensor is held by a single 10 mm bolt.
With a helper watching the speedometer with the ign. on, give the sensor gear a spin with a flick of the fingers and see if the speedometer pointer jumps. This would show that the sensor and wiring is OK.
 

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Well I poked around and don't see how the heck I'm gonna be able to get at that area. I think I've probably reached my comfort limit and will turn this over to my mechanic. I appreciate your giving me an edge in getting the right repairs done without alot of extra diagnosis time. I'll post back when I get a little further on this problem.

Thanks, John
 

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Discussion Starter #9
Gave up un the problem for a while and got a used Garmin at the pawn shop to use as speedometer.

In the mean time I had the speed sensor replaced at a small shop and speedometer still does not work.

Error code P0501-VSS #1 performance PCM does not see speed signal from transmission control side of PCM.

Does this tell us anything useful?
 

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Pull the speed sensor back out of the transaxle and with a helper watching the speedometer with the key on, give the speedometer gear a 'flick' to turn it quickly. The speedometer needle should jump.
If it jumps, then the sensor, wiring, ECU and speedometer are OK.
There is a white nylon speedometer worm drive gear on the differential that drives the gear on the sensor. The nylon gear may have broken.
diffinterference2.jpg
If you can poke down there in the hole and move the nylon drive gear on the differential with a screwdriver tip, then the gear is probably broken. The transaxle case halves would have to be separated to service the gear.
 
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