Tach Drops Out

[bhoff]

My latest minor issue is the tach occasionally not working. It happens on starting where the tach does not register anything. If I shut the engine off and restart, the tach will work. This happens about 1 out of 5 times starting now. Was just very occasional in the past. Sounds like a bad connection somewhere. Wondering where the tach gets its data from and where I should check. Thanks for any help.

[GH85Carrera]

What year and model is your 911?

[Bob Kontak]

I don't know the exact symptoms but some tach issues can be caused by a faulty voltage regulator. Put a multi meter on your battery posts and check the DC voltage. If it varies over a volt or two then the V reg needs to be replaced. The easy test is to check your headlights - if they change in intensity the V reg is tired.

[1976 TN Porsche]

Thanks for the info mine does the same thing.

[Won]

On my 83, one of the circular rubber connectors on the firewall beneath the ignition switch was loose and causing intermittent tach dropout as well as non functioning wiper. Make sure they connectors are plugged in tight.

[bhoff]

It's an 87 cab with 124,000 miles. I replaced the alternator/regulator about 2 years ago. Voltage checks out ok. I am pretty sure that I have a bad ignition switch because the radio and spedo sometimes do not work (fed off of the same wiring?) If I move the key slightly, they will come on. Tach does not seem to be connected to this same feed. If the tach does not come on, I shut the engine off and restart. Comes right back up.