Paolo928

Hi there,
the rpm gauge of my 1983 Porsche 928s 5sp works whenever it wants, if it wants to, almost never when I need it. Like today, when I was adjusting the idle it stopped working and still now doesn't. Is there a relay for it in the fuse panel or a connector that I can check?

miekojarvi

Check and clean the connectors on the back

Paolo928

Hi miekojarvi, thanks for the replay.
I did look at the connectors in the battery compartment. I found one wire disconnected. I put it back in place and the speedo started working again but the rpm gauge still doesn't work ...

steve322s

i had the same problem eventully it stopped all together ended up it was a resistor in the tac. you can send it out for repair. i just changed mine with one from a parts car. good luck

Paolo928

Thanks steve322s...
it seems like mine has stopped working for good. It didn't move for more that a week now.

Optimator

I had an odd failure on my tach recently. There is a capacitor mounted on the internal PCB. It had swelled until it physically hit the tach needle movement and pinned it in place at rest.

Mrmerlin

the back that miekojarvi is talking about are the connections on the back of the gauge cluster.
There are pins that plug into the flexible wire sheet clean these, your tach should work ,
otherwise give the pod a tap on the top with your hand some times that will jostle it to life

steve322s

If i remember correct 3 and 5 were power and signal, I have power, and used a test light on i believe connection 5 and as i reved her the light got brighter, still no tach, checked G7 the same way and test light got brighter, all other gauges are working correct, does the tach share the same ground with the other instruments?

I tried this first, turns out to be a good way to test at the fuse panel, if you have these working then check them at the pod circuit board, if that too is working pull the tach itself and try using jumper wires to see if it will work. my tach stopped working and i cleaned everything before it stopped working and all my gauges and lights work. took my spare tach jumpered it first at the fuse panel because it was pulled from a flood victum and it worked. after som testing on the old one i found a bad resistor by checking ohms.

Good luck.

F18Rep

How about another Reflowed-in-Moms-oven project. I think the recipe called for 400 for 8 minutes. Loved that one. ...;]

Paolo928

I found this simple diagram... #8 goes to the tacho. I opened the hood and messed a little with the plug. Then I turned the car on and surprise: it works!
Is hard to get to the plug (radiator hoses are in the way) but I definitely have to clean up those connections.
No baking for me

Paolo928

Sorry, I'm having trouble with inserting pictures in my posts.
Here is the link: http://www.flickr.com/photos/27417040@N03/8270675565/

Paolo928

Never mind, it stopped working again and so did the speedo.
Tacho is dead at the very bottom and speedo is acting funny:
When I turn the key it jumps to 50 mph and when the engine comes on it settles to 30 mph.
I guess is time to take it in pieces and see what is going on in there...