2014 Ford Escape SE 1.6L

This vehicle was towed to my home. Owner complaint was after driving sometime, as he steps on the accel pedal, there is only a high RPM and transmission seem to slip with the vehicle unable to run. He turned off the ignition and waited for a few seconds and it drove fine for a short distance and the same sympton occured. DTC showed a permanent fault P26B7 - engine coolant bypass valve open and a P1299 - cylinder head overtemperature protection active.

I did an initial test fo the coolant bypass valve: KOEO, (1) one wire showed 12.36 V (violet/brown wire) and (2) the other 35.6mv (yellow/gray wire) instead of 12V without being energized...I dont have a wiring diagram and I want to test the control wire at the PCM. Any tips/suggestion is welcomed. Thanks

Sure sounds like that bypass valve is electrically open! :silly: From the description and operation, it sounds like the PCM won't open that bypass until 158 degrees. Ain't nobody got time for that.

I wonder if you connect a test light to B+ and probe the bypass control wire, and hit the KOEO Self-Test, you could get the driver to operate? That'd be a lot faster than waiting for the engine to warm up.

A bidirectional function would (hopefully) do the same thing. If the test light shines, you're good to go with a new bypass valve.

I agree with Tyler that a test light would be a worthwhile test. Unplugging the solenoid and putting the light across the terminals might work better?? Then KOEO the light shouldn't be stuck on but might illuminate briefly as a self test. If the wiring to PCM is good that should allow the code to be cleared unless the monitoring is smart enough to measure solenoid resistance.

I don't have a good feeling about this one though. The two P codes seem loosely related to the customer complaint......

unplugging, KOEO, TL (+), probing control wire and performing self test, TL lit confirming driver Ok; likewise voltmeter showed a drop in voltage as driver commanded on. Replaced the bypass valve . out of curiosity, KOEO, voltmeter read 12V on each wire ! This portion of the problem was FIXED.

However test driving it around, shift was still rough and tranny was still slipping. A new code this time showed : (1) P0731 Gear 1 and P0733 Gear 3 incorrect ratio; (2) P0219 engine overspeed condition.

I advised owner to have his tranny checked by a specialist.

As for the bypass valve, this is a FIXED.

Stick a fork in it, 'cause it's done. :silly: Those transmissions are absolute junk.

Thanks for the update.

robert.lesaca wrote: Replaced the bypass valve . out of curiosity, KOEO, voltmeter read 12V on each wire !

That's normal for a ground side switched circuit when it's commanded off. With no path to ground there isn't any current flow to cause a voltage drop across the solenoid.

correct...12V in and 12V out KOEO.