tach lead

[11secondgs]

tach lead

Guys - I am installing an aftermarket tach in my analogue car....now I know the green lead behind the alternator is teh tach lead, but mine is missing becuase the hack that had my car before me cut the wiring up pretty good.

I am out to solve it.....so, where can I trace the tach wire back to towards the firewall?

What color is the wire?

Where can I find inside the car behind the dash?

thanks for any help.

The worst thing ever is fixing someone elses wiring mess.

 

[garyk1970]

the tach lead is actually white. the test port behind the alt has a green plug,but the wire is white.
look for a white wire at coil, pcm,dignostic plug,etc.

 

[11secondgs]

the tach lead is actually white. the test port behind the alt has a green plug,but the wire is white.
look for a white wire at coil, pcm,dignostic plug,etc.

Do you know where exactly inside the car the tach wire is? I would like to trace it but don't know exactly where pcm is????

I would just like to splice it in the car.

Also, does the wire connect to the crank trigger somehow, or does the signal get processed first, then turn into a tach signal?

I would like to splice it from inside the car, but tried looking all over for a white wire and saw about 3 white wires? Wheres a good spot in the car I can for sure see it and splice?

 

[garyk1970]

Do you know where exactly inside the car the tach wire is? I would like to trace it but don't know exactly where pcm is????

I would just like to splice it in the car.

Also, does the wire connect to the crank trigger somehow, or does the signal get processed first, then turn into a tach signal?

I would like to splice it from inside the car, but tried looking all over for a white wire and saw about 3 white wires? Wheres a good spot in the car I can for sure see it and splice?

not 100% sure. take the time and run a wire through the firewall and find the white wire behind the alternator.

tack signal comes from the coil control module?

the ecm/pcm is behind the pass kick panel.

white wires inside the car are either ground switch for the dome light circuit,or tack.....put volt meter on ac and ground,tack lead volts will increase when you rev engine.

 

[Jerryl]

not 100% sure. take the time and run a wire through the firewall and find the white wire behind the alternator.

tack signal comes from the coil control module?

the ecm/pcm is behind the pass kick panel.

white wires inside the car are either ground switch for the dome light circuit,or tack.....put volt meter on ac and ground,tack lead volts will increase when you rev engine.

You can also get the RMP signal from the ECM connector
Fuel Injection ECM Pinouts Pin-B5 ( I think )

My Zeitronix WB set-up has an RPM input signal and I connected to the ECM harness somewhere. It works fine.

 

[TurboDave]

If you can't find the pair (yes there's two) of white wires near the alternator, one of them comes from the coil module. I'll have to double check the pin number, but it's the rear most (closest to firewall) white wire on the module plug.

Just checked, it's pin A on the module (rear most), or pin B4 (not B5 jerryl) on the ECM.

 

[11secondgs]

where exactly is pin B4 on the pcm.....is it labeled.

 

[TurboDave]

Hopefully I wont screw this up:

Of the two connectors, it's the smaller one closest to you. The "B" row is the inside row, closest to the glove box. The numbers start with 1 (closest to you) and work toward the firewall.

Somebody correct me if I'm wrong, working from memory here at work.

Here's a link to my drawing. Look in the lower right corner where the two ECM connectors are shown (as if you're looking down on them).

http://www.gnttype.org/techarea/ecmsensors/regal_ecm.jpg

When the picture comes up, click on it once and it should zoom in.

 

[11secondgs]

Can I get the tach signal at the ALDL port somewhere?

Where on the computer do I splice to get tach signal. I heard B4 was not to be touched?

Please help I am doing this as we speak in my driveway.