HELP: Need Tach Signal!!

[Lil Abner]

Does anyone know where I can get a tach signal inside the car? I would rather not grab a signal off the engine. There has to be a signal at the Body ECU, but my o-scope is broke so I can't find it.

Any help is appreciated!!

[Jeff Lange]

There isn't one.

Sorry.

Jeff

[Lil Abner]

I don't believe that. There has to be a tach signal for the OEM tachometer in the gauge cluster. Unless it's in a data stream from the engine bay...

[Reason]

Here you go: http://www.ft86club.com/forums/showthread.php?t=10292

Originally Posted by jedibow

Thank you Don!

So that everybody will know, the tach wire is located behind the drivers side cylinder head, there is a harness with black, and black and grey wires this is where you need to clamp.

Should be able to follow that to its termination, however it very well may terminate in the engine bay into a control module, and not go all the way to the ECU in the cabin.

[Lil Abner]

Hmm. Thanks, but still not helping. I'm hoping someone knows what pin on the Body ECU under the dash is the tach signal. I hate splicing into wires in the engine bay.

[Jeff Lange]

The tach signal is communicated between the Engine ECU and Gauge Cluster, etc. on the CAN BUS. There is no single wire for tach, it is a data stream.

I didn't just guess before I posted, I looked it up first.

Jeff

[Lil Abner]

Originally Posted by Jeff Lange

The tach signal is communicated between the Engine ECU and Gauge Cluster, etc. on the CAN BUS. There is no single wire for tach, it is a data stream.

I didn't just guess before I posted, I looked it up first.

Jeff

Ok, thanks. I guess I'll do some solder/heat shrink under the hood...

[vividracing]

Originally Posted by Lil Abner

Hmm. Thanks, but still not helping. I'm hoping someone knows what pin on the Body ECU under the dash is the tach signal. I hate splicing into wires in the engine bay.

Why do you not want to grab the tach signal in the engine bay? With a little spray silicone you should be able to run the wire through an existing hole in a grommet.

[Lil Abner]

Originally Posted by vividracing

Why do you not want to grab the tach signal in the engine bay? With a little spray silicone you should be able to run the wire through an existing hole in a grommet.

I actually already have wires run into the engine bay for the tach wire as well as for my amp. I just dislike tapping into a wire under the hood with the Michigan/Ohio winters. But since that's the only source, then I'll have to run with it.

The schematic I'm using shows 4 tach signals on the passenger side large connector. So I'm going to try those.

[PrimeMotoring]

If theres a red/black at the obd 2 connector you can get tach there.

[vividracing]

Originally Posted by Lil Abner

I actually already have wires run into the engine bay for the tach wire as well as for my amp. I just dislike tapping into a wire under the hood with the Michigan/Ohio winters. But since that's the only source, then I'll have to run with it.

The schematic I'm using shows 4 tach signals on the passenger side large connector. So I'm going to try those.

Oh yeah, I forgot winter even existed. We have a few months out of the year that require a hoody and jeans but that's it.

[Jeff Lange]

Looking into it further, it looks like the ECU has a dedicated "TACH" output signal, pin A35-15 on the ECU. This is the 35-pin connector.

It probably heads over to the DLC2 connector or something, because it isn't heading to any other systems in any of the wiring diagrams which is where I initially checked. Every other ECU, etc. uses the CAN-BUS to get the tach signal, but as I said there is an output dedicated to it on the ECU. It's not shown in any wiring diagrams, but it is mentioned in the RM.

Nice of them to do that.

Jeff

[xcelir8brz]

subscribed.

[cruzinbill]

subd as well... if jeff lange is on top of this research it will be no time at all till a definitive answer. Guy knows his shit.