TCIL flashing during driving

[sitruc_btb]

Hello everyone, I recently acquired a hand-me-down Expedition. Just received it Christmas Eve. The vehicle is previously from Washington state, and now resides in AZ. It came here on a car hauler, which took about a month. No problems prior to its arrival, however, when I drove it home, I noticed the O/D light flashing, and the Expy did not like to go over about 43mph. Attempted to pull some codes at work, but my Ford resources are limited to a Snap On scan tool, and AllData. What I did find was a DTC P1270, excessive engine RPM/Vehicle speed. Never happened before the vehicle was transported. Any input is appreciated. Thanks!

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[bedrck46]

have you cleared the code if not reset it with the scan tool or disconnect the battery for about 10 minutes and then try again and see if the code reappears

 

[sitruc_btb]

I have not. I will disconnect the battery tomorrow and cross my fingers. Thanks.

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[bedrck46]

keep us up-dated

 

[sitruc_btb]

Definitely!

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[sitruc_btb]

I disconnected the negative battery cable for about 15 minutes or better, then test drove it. TCIL came back on. Was not able to pull s code, because the office where our scan tools are located, was locked up for the evening. That's all I was able to do today.

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[bedrck46]

get the scanner read the code then reset it using the scanner hope that helps

 

[sitruc_btb]

Connected the scanner again, found no present codes.Test drove with scan tool connected. TCIL starts flashing. Pulled a DTC P1729, 4x4L switch failure. Printed off a flow chart I found on Alldata, regarding the DTC. Perhaps something got damaged during transportation.

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[bedrck46]

sounds like they beat the s__t out of it before you got it if you need elect prints on the 4x4 system let me know

 

[sitruc_btb]

Yeah Ill take whatever information you have. Thanks again man.

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[bedrck46]

what year and engine

 

[rollavvti06]

Dumb question but is it in 4x4 low put it in neutral and see if it switches to awd or 2wd. And ale sure that switch is in awd or 2wd

 

[sitruc_btb]

1998 4.6L

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[bedrck46]

ok Thanks for the comeback as the 98 has a 4x4 switch that has a 2wd position and the 99 and up doesn't I'll send you the correct prints for a 98

 

[sitruc_btb]

I put it in neutral, and when I turn the knob from 2wd to awd, the awd light illuminates, but when I turn the knob to 4wd, or low range, those lights do not illuminate. The awd lights stays lit, even when the knob is in 4wd or 4lo position.

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[bedrck46]

Prints attached 97 and 98 are the same

also remove the mode switch and check the resistance in each position
Measure the resistance between mode switch terminals 2 and 3 while rotating the mode switch through all positions; refer to the following chart:
Switch Position Resistance Range
2H 3705-4095 ohms
A4WD 1425-1575 ohms
4H 646-714 ohms
4L 228-252 ohms

 

[bedrck46]

1)The Vehicle Does Not Shift Between 2WD/A4WD and 4WD Modes Properly

A4WD mode switch/circuit.
A4WD clutch relay/circuit.
Contact plate sensors A, B, C and/or D circuits.
Transfer case shift motor/circuit.
Transfer case shift relays.
Transfer case mechanism.
GEM.

2)The Vehicle Does Not Shift Between 4WD HIGH and 4WD LOW Modes Properly

A4WD mode switch/circuit.
VSS.
BPP switch.
Transfer case shift relays.
Transfer case mechanism.
Transmission range sensor.
GEM.
Digital transmission range (DTR) sensor

3) check the operation of the brake switch just because the brake lights come on doesn't mean that the switch is 100% ok there are two circuits that go through that switch one for the brakes and the other is part of the 4x4 circuit

 

[sitruc_btb]

Awesome. Thanks for schematics and values.

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[sitruc_btb]

The 4x4 drive mode switch resistance values are within spec.

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[sitruc_btb]

Today I was able to play around with the Expy some more. Cleaned up all the fuses and battery cables/terminals. Tested the 4x4 mode switch the other day. Switch is good. Pulled up a data list on our Generic scan tool. PCM is reading the switch changing from 2wd to a4wd, 4hi, and 4lo. Scan tool also sees when the brake switch is depressed. I checked the connectors around the Transfer case shift motor. Wiring and connectors looked ok. I did notice a hum coming from the transmission when the ignition is in the "on" position.