tach signal wire?

Originally Posted by Corporate666

Sorry to bump this thread after 3 years, but it's highly ranked on Google so I thought I would post an update.

The tach wire is Pin #110 on the ECU (sometimes referred to as pin #14 since it's the 14th wire on that plug...each column has 4 pins, it's the 4th column in, 2nd pin up).

On my 2010, it was easy to determine which wire it was because the connector has small pins on one side and large pins on the other. Start from the side of the connector with the small pins. Count over to the 4th column (the connector is something like 8 columns, 4 rows). Then count up to the 2nd row.

It doesn't matter which side you count from as row 1, because if you count from the wrong side, there is no pin in that hole on the connector. You can insert a flattened out staple into the hole and you will immediately feel if there is a terminal in there or not - if not, it's the 2nd row counting from the other long edge of the connector.

The wire coming out of it is red. In the bunch of wires, there are 2 thin red wires and at least 1 thick red ride. It was one of the thin ones. I just used a meter to determine which it was.


The tach signal itself is a 5 volt peak-to-peak square wave (0V to 5V) and produces 3 pulses per revolution.


The ECM itself is behind the glove box. I took my glove box out to get to it - it's real easy to do. Just pull the trim panel off of the door kick panel (no tools, just pull up and towards the center of the car). Then there is a little plastic nut way in the corner of the passenger footwell - pull that off, then that lower corner panel just pulls out. Then open the glove box... there are 4 screws along the top - remove those. There are two screws just visible at the lower corners of the glove box which are exposed when you open the box - remove those. Then there is one more behind the glove box door - pain in the *** to get it but a long screwdriver will get it. Then just pull the glovebox and it will come out. The ECM is right in front of you mounted parallel to the centerline of the car on a metal bracket. The large wire closest to the rear of the car (closest to you as you are sitting in the seat looking at it) is the one that has the tach signal wire in it.