Allison erratic after fording

NDT

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Guys, have not had time to dig into this yet, but lots of times ya'll have been down similar paths and have quick fixes. '98 M1079 with WTEC 3. Shifted great until start of fording ops during 4 hours of high water rescues last night. Symptoms: would not shift out of 2nd sometimes, 7 showing on keypad after pressing D. Sometimes, would start off in 6th and stay only in 6th, keypad showed 6 after pressing D. Pressing N would not engage neutral, had to kill engine/restart to get neutral.
No water in cab or dripping on keypad. Obviously transmission got very wet. Have not pulled codes, it was 3 am.

Ideas?
 

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Suprman

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The trans harnesses are more prone to the wire insulation getting dry and cracking/falling off. Shorts happen. Usually where the harness turns. Where it comes out of the drivers side hump is common. You can get water in that connector also. Pull the grill and you can carefully use channelocks to twist disconnect it. Outside only, inside is wired to the bulkhead. At the trans there is a pigtail coming up a foot or so and another mil cannon style connector. Look for water infiltration there too. Hopefully no water got in trans.
Will
 

NDT

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Now getting flashing "7" only, no engagement. Code is open circuit to one solenoid. Reseated the connectors at the cab and transmission, no help. Looks like time to break out the ohm meter.
 

Suprman

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The computer expects the wire harness to be good. It just sees an open circuit. I believe it does a quick continuity check before it shifts.
 

NDT

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Yes. Computer checks for open circuit and short circuit on each solenoid circuit. There are a pair of wires for each solenoid. Neither wire is grounded.

Oil is fine, we only forded like 2 feet depth.
 

NDT

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Resolved. Reseated all three cables at the WTEC3 controller behind the passenger kick panel and normal operation resumed. Amazing how even with gold terminals, resistance can still build up over 20 years and cause the self check ohms to fall out of spec.
 
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