Tach Wire location by engine? Where can I get to it?

[2k1Toaster]

I am looking for the tach/engine-speed signal by the engine. I can attach my probe to the white/gray-ish wire running into the RPM relay in the cabin by the fuses, but I would really like to find that wire somewhere by the engine.

Any hints?

I have the cover near the front-passenger side of the engine compartment where all the wires plug into housings and (presumably) goes through the firewall into the fuse area. I can de-clip it, and see all those connections, but I don't really see the correct coloured wired there. I assume they would be matched. But they are rather dirty too.

[Ron]

You can get the tach signal at the RPM Relay, the Ignition Control Unit or Idle Speed Control Unit (ECUs) in the in the compartment behind the driver, or right off of the coil (-).
Grey/Slate tracer

[2k1Toaster]

You can get the tach signal at the RPM Relay, the Ignition Control Unit or Idle Speed Control Unit (ECUs) in the in the compartment behind the driver, or right off of the coil (-).
Grey/Slate tracer

Yeah I saw that in the diagram. The RPM Relay, and ECUs are out since they are internal to the cabin. I need something in the engine bay, something I can hook up my oscilloscope probe to safely.

The coil is behind the front-passenger area cover in the engine correct? I know one side is the kilovolt side and the other is the low voltage tach side. Is there a pretty easy way to determine which side is which. I have never looked at it other then the 10 seconds I shined a flashlight through the gap in the cover and saw it in there (I think).

Speaking of which, is there a way to get that cover out after it clips off? It seems "sandwiched" in there by hoses and such. Is there a trick to that?

[David T]

If all you need the signal for is to read RPM, get a timing light with an inductive pick-up and a built-in tach. Another way to read RPM might be to try to utilize the pick-up that terminates in the diagnostic plug.
David Teitelbaum

[DMCMW Dave]

the other is the low voltage tach side. Is there a pretty easy way to determine which side is which. I have never looked at it other then the 10 seconds I shined a flashlight through the gap in the cover and saw it in there (I think).

Speaking of which, is there a way to get that cover out after it clips off? It seems "sandwiched" in there by hoses and such. Is there a trick to that?

Just reach under the cover and pull it off. The hoses will move and the cover is slightly flexible. The fun part is putting it back.

The wire you are looking for should be white/grey and on the (-) side of the coil (there is a + and a - sign cast into the coil plastic next to the two small connectors). Unless someone wired the coil backwards.

The "kilovolt" side that you refer to is the huge wire coming out of the top of the coil, should not be much of a confusion between that and the tach wire.

Really an easier place to connect your scope is probably that same wire on the RPM relay in the electrical compartment. Why is it so necessary to connect in the engine compartment? It's not like the interior of the car is hard to get to.

[Ron]

WOOPS!...Sorry!

I typed White/Grey but thought the tracer might be Slate and when I looked it up and returned to fix it, I screwed it all up somehow...
(Thanks Dave)