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Hard to find electrical problems
Posted to Technical Tips Forum on 12/1/2013 12 Replies

I think one of the most important things NOT to do is move the wire harness when trying to verify the customers concern.

I am working on a 2006 escape 2.3 auto 4x4 with 60,000 miles.

Step one, recreate customers issue.

Step two, find the problem.

Step three fix the problem.

Step four, make out the bill.

The concern was reverse that would engage and disengage and a speedometer that at times would hang at 20 or 40 mph.

I got in the car with the scanner plugged in, put it in reverse to back out of the parking spot, as the accelerator pedal was touched it quickly disengaged and engaged the trans abruptly. My first thought was a broken or loose MLPS connector. I had one code p0707 I think.

The in and out of reverse was very very quick and harsh, so I was very careful moving it. I brought it in the shop to have a look at the connector and sensor. Nothing I saw looked bad or out of place, except the new MLPS.

I knew I was the third person to look at it for this concern. Now I have looked at the scan data for the mlps as I gently moved the connector and wire harness. Nothing shows up at all, remember I have tried not to MOVE anything without knowing that I did.

Next I try reverse and it works perfectly, no disengagement or speedometer issue. Now what did I do to change the problem? I don't know.

Now I walk away for a bit. When I come back I put my scanner pid on just the mlps voltage in graph form, move the harness and low and behold I have a zero volts on the graph for just one recording frame. The mlps must have a bad connection. No dice, everything is perfect. I start a new graph and realize that as careful as I am, my left elbow is moving the harness at the back side of the cylinder head.

Now I can recreate the problem with a gentle push on the wire harness that is 18 inches from the sensor. I found it, 2006 Ford Escape XLT, Transmission Photo 2006 Ford Escape XLT, Transmission Photo 2006 Ford Escape XLT, Transmission Photo

The learning curve is steep with electrical issues. Be very easy when moving something when trying to recreate the issue. Going at it, without knowing what you are changing always ends with, [can not duplicate customer concern]. Never good as the customer is looking at you thinking it does it every day for me.

Take your time and be very diligent with respect to knowing what you are touching.


Dan from Wisconsin

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