Tach Attack

[wscheffer]

Hello Everyone,

I have a 1987 420 SEL that the tachometer has not operated since I bought the vehicle earlier this year.

I am presently doing a dash out application involving the replacement of the evaporator on my A/C system. Oh Boy what a job, but this would be another thread!

Anyways I was wondering how to test to see if it is the Tach at fault or if it is something else.

My question is!

Would it be safe to test for signal by clipping an electrical lighted test probe to the wire that plugs into the back of the Tach and touching the tip of the electrical lighted test probe to ground while the engine is running?

If the test probe flashes I have signal and it's the Tach that is bad or no light flash meaning the fault is elsewhere.

Or will this damage the EZL?