Hey folks,

This is for a 2000 C5...

I've got everything hooked up but cant seem to get a good tach signal. TPS is fine. Here is what I have done:

1. Located white wire at the PCM (pin 10), and crimped in with the white tach signal wire from my MSD window switch using a T-connector. I ran this up to near the battery (my Wideband commander and MSD switch are located on top of a batter cover).

2. tapped into the MSD tach signal wire with another connector, and used the orange wire on the WB commander, which should be the tach signal wire.

3. Started car, fired up the wideband software, and no RPM value on the laptop (but the TPS was fine).

4. I then cut the WB commander orange wire and tried tapping each of the 3 white wires under the passenger side of the dash - still no signal.

5. I then put male/female disconnects onto the orange wire which I cut before, and then reconnected, and noticed an intermittent tach signal. I would ONLY get signal at the instant when I touch the connectors together, or when I pulled them apart. When fully connected, no signal.

6. I have tried changing the multiplier and the sensitivity in the software - no luck.


I havent tested the window switch yet, could this be interfering? Maybe this weak signal will prevent the MSD switch's operation too - or maybe it is the cause. I am getting the intermittent signal, so I am pretty sure I tapped the correct wire off the PCM - maybe the tap itself was bad? the tach in the car still works just fine so the wire didnt sever.

I don't think the ground is bad cuz the TPS value is read just fine.

My best guess at this time is the tap wire running down to the PCM is suffering interference since it is based on frequency and not voltage? It is running straight down to the PCM, next to the battery and near the positive battery terminal...

Thanks in advance for the help!

 

I'd double check connection thru the wiretap.I had a similar problem with my setup and it was the wiretap.FWIW.


joel

 

So did you finally make it work?
I am asking because it seems I have the same problem. My WBCommander does not sense rpm. I know I wired everything fine and connected to the right wire as I have also a shift light and NX Maximizer connected to the same tach signal and both these units work fine.
Any good advice?

 

Mine seems to be working off and on. I tested the voltage with a multi-meter and with the car on it reads around 6volts when the signal comes thru successfully. When the signal is not picked up, it is because the voltage has dropped to 2-3 volts. I have no explanation for this... right now I am just happy when it works, and when it doesnt I fiddle with the wires a bit and sometimes it fixes itself lol.

I checked the voltage of the three white wires under the passenger dash and I couldnt get more then a 0.20 voltage reading on any of them! I am still as confused about this as ever lol.

And yes, I know that the signal works on Hz and not voltage... its just that when the signal isnt picked up the voltage has dropped to below 3 volts on the tap wire.

 

Thanks for the info.
And how did you set sensitivity (low/high) and divider (0-32) in WBCommander?

 

sensitivity = high and divider = 4 (or 2? lol) if I recall correctly. Once you pickup signal, just change your divider till the RPM matches your tach.