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.

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sparky

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

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My ex once told me I have a perfect face for radio.

i am an idiot wrote:

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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.

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

sparkie wrote:

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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.

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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:

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

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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.

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Soldering is fun!

i am an idiot wrote:

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Rev the motor and the voltage should increase.

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

kreg357 wrote:

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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.

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Thnx for the input. I did check the OBD and the wasn't a wire at pin 9 but next time, I will try to see if the device would learn Tach from that wires.

And so if I understand you correctly, a remote start signal can never learn Tach from a non true Tach wire right?

And so if I understand you correctly, a remote start signal can never learn Tach from a non true Tach wire right?

Basically, yes. If it is not a good Tach signal, it won't successfully learn the signal. But actual remote starts when the engine is cold, warm, hot and various weather conditions are the true tests. I have had good Tach Learns but over-cranks when hot and no-starts during real low temps. Every vehicle and R/S brand can yeild different results.

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Soldering is fun!

kreg357 wrote:

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And so if I understand you correctly, a remote start signal can never learn Tach from a non true Tach wire right?

Basically, yes. If it is not a good Tach signal, it won't successfully learn the signal. But actual remote starts when the engine is cold, warm, hot and various weather conditions are the true tests. I have had good Tach Learns but over-cranks when hot and no-starts during real low temps. Every vehicle and R/S brand can yeild different results.

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Ok. Thnx for the info.