Testing Tach wire at instrument cluster

I was testing the Tachometer wire at the instrument cluster on a 2009 Toyota Sienna and according to ReadyRemote --> white 40 pin plug, pin 37 Well I did find the exact wire & color at the pin but when I set my multimeter to AC and rev the engine, I got a reading btw 6-7V with engine at IDLE consistently. Reving the engine really didn't change it. So I tested the wires at the fuel injector coil (non-common color) and the reading was going from 0.1 to 0.9V and revving the engine made it jump up. Any ideas? I ended up just going Tachless and adjusted crank time. Didn't want to run a wire to the engine bay. Yes am lazy.

Try putting the meter to DC volts. The voltage is actually a pulsating DC signal. Some meters will fluctuate with engine speed when on AC volts. Some meters need to be on DC volts.

I have the tach wire listed as a BLACK/ Orange wire in pin 37 of 40 pin plug at cluster. Make sure that your meter has a good ground and you are getting a good contact to pin. Set meter to AC voltage.sparky

Bulldog lists BLACK/ orange pin 1 of the 35 pin ECM connector- behind the glove box.My ex once told me I have a perfect face for radio.

i am an idiot wrote: Try putting the meter to DC volts. The voltage is actually a pulsating DC signal. Some meters will fluctuate with engine speed when on AC volts. Some meters need to be on DC volts.

When I set my meter to DC volts, what reading should I be getting to look for? Thnx

sparkie wrote: I have the tach wire listed as a BLACK/ Orange wire in pin 37 of 40 pin plug at cluster. Make sure that your meter has a good ground and you are getting a good contact to pin. Set meter to AC voltage.

Yea I found that exact wire. Since ReadyRemote had a picture of it, is was hard to miss. My ground and other connections were fine -- I used the same ground to test the wires at the ignition harness as well as Arm/Disarm wires...

geepherder wrote: Bulldog lists BLACK/ orange pin 1 of the 35 pin ECM connector- behind the glove box.

I also went behind the glovebox to test that wire too using @kreg357 pictorial guide and got the same reading I got at the instrument cluster. I use the INNOVA 3320 for my testing

Rev the motor and the voltage should increase.

When it comes to the Tach wire, I have found that you can attach the R/S Tach Input wire and try a Tach Learn safely without causing any harm to the vehicle. With the R/S units I use, the Tach Input wire has a very high impedance and places virtually no load or interference on the vehicles Tach wire. While it is best to use all available wire guides and other info sources to locate the wire and run the DMM test on it first, sometimes the real test is the actual Tach Learn. If you have a high-end R/S system, you can always go to a F.I. or Spark Plug Coil, plus on many Toyota's, Pin 9 of the OBD2 plug has a Tach signal.Soldering is fun!

i am an idiot wrote: Rev the motor and the voltage should increase.

Ok so next time I will try it in AC & DC mode...