Robbe

Hi All,
my 968 has a problem with the odometer.
It started working erratically some weeks ago, and now has fully stopped working.
As the whole internet is full of instructions on how to change the (broken gears), I was fully confident to have it fixed fast.
So i removed the dash /instrument rim, removed the complete cluster (trick is to diagonally slight it out, works perfectly without having to remove the airbag) and removed the speedometer.
When I unbolted the stepper motor, nothing broken fell out, and all was still intact.
I cleaned everything and freshly lubricated it with thin watch oil, and manually it works perfectly.
But when again installed back in the car, still only the speedo works, no odometer or tripmeter.
And as a bonus, I now have an airbag and central warning light...
I checked all connections several times, nothing broken or corroded....
So must I suspect the stepper motor now? And how do I check that?
Anybody? (and any ideas on the airbag ligt?)
Thanks sofar!

Jfrahm

Did you get an ABS warning before your speedo quit? The speedo runs of the (um... Left Front?) ABS sensor via the ABS module.

It's worth checking for that tone ring signal to the AMS module and the ABS module to speedo pulse train.

You will need a computer interface tool like Durametric or the Bosch Hammer to reset your airbag warning.

-Joel.

Robbe

Thanks, but the speedo still works as it should, it is only the odometer (and tripmeter). No ABS warning light.

Anybody any ideas why I would get an airbag warning after reinstalling the cluster? Or did I already have that warning, but because of a non-100% connection before I reinstalled it, it did not show?

joes

Yup,
if you turn the key on while the gauges are unhooked you will have an air bag light because the gauges are part of the system. There is a guy http://www.bergvillfx.com I bought adapters that plug into the 968 and then to a laptop from him. Then there is shareware to download to the laptop that will access/ clear the codes. it's supposed to be for a 993 but works with 968 as well.

Robbe

Ok, that is clear then, thanks!
So no worries about a ready-to-explode-because-instabile airbag I guess...

I am thinking of replacing the stepper motor as I suspect the problem is in there somewhere.
It is not supplied as a spare part as far as I can see in PET, but maybe other brands that used VDO do?

FRporscheman

Maybe it's a bad solder joint on one of the speedometer boards / jumper wires. You might also want to check continuity from the external cluster plugs to the odometer motor.

Also, I was just replacing an odo gear in a 968 yesterday. I noticed it's really finicky about getting the gear shaft (which is spring-loaded) to go back into the hole in the clear plastic housing. If it doesn't, it will bind and not allow the gears to turn. I had to redo the job because of this, that's how I know.

But if you're saying it happened spontaneously, before you opened the cluster, then it sounds more like an electrical problem.

Robbe

"I noticed it's really finicky about getting the gear shaft (which is spring-loaded) to go back into the hole in the clear plastic housing. If it doesn't, it will bind and not allow the gears to turn. "
You mean the stepper motor shaft?
I do not recall having had a problem with reinstalling the gears at all, it bolted back on in really a few seconds without finicky work, so maybe I missed a part there???
I will remove it all again to have a look.
When I manually turned the gears (before bolting the stepper motor back on), it turned freely (as long as I centered the large gear of course, otherwise it binds)

FRporscheman

Yes, the stepper motor shaft. The tip of it needs to sit inside a hole in the clear plastic odometer housing.

I had the exact same experience - I had no difficulty in reassembly, and everything worked smoothly when tested by hand before reassembly.

I wish I took a picture, but if you're taking it apart again, you'll find out soon.

Luis de Prat

Same issue here on my 91 951. Took it apart several years ago to replace the gear, and it turned out it had the modular 968 set up.

I read somewhere it's the shaft that comes loose and wiggles around not letting the mechanism function properly. I've had the assembly out before, as I said, but it really pains me to take it out again for no reason.

FRporscheman, how did you affix the shaft to the housing? Glue?

Thanks

jhowell371

Another possibility: http://www.arnnworx.com/catalog/inde...a96eb56d03caa0

thomasmryan

I re-used the old follower after installing the inoperative aftermarket gear set. It worked so I didn't question why.

Bench3490

I have a 1992 968 with inoperative trip/odometer. Had the cluster sent away and replaced stepper motor and gear. Both of which appeared fine before they were replaced as per tech. Circuit boards appear fine. Am I missing something? What other possibilities could there be?

931guru

Bad circuit board. "It's dead, Jim!"

Dwad

Hi,
in my case( Porsche 968, 1993) none of the speedo & odo works.. I understand that odo should not be working as one of my gear is cracked, but it should not affect the speedo right, Speedo does not has to do anything with gears right......
While I checked the continuity from external connection of cluster to Speedo connection( 3 holes for ground, signal & power), all are ok... But from the 3 hole connection to inside of Speedo gauge I could was not able to find ground continuity.... yet I can find power line continuity to inside of gauge....it could be problem ?
thanks
Hope I am making sense.

potent951turbo

As already posted above and if you do a search I’ve posted this before. The 968 and 993 very commonly have the stepper motor go out which will cause the odometer to stop working. Send the cluster to North Hollywood Speedometer, it will be the best $150ish dollars you ever spent.