Sick AW4

[Ecomike]

The loss of ground was rare (once or twice on a 5 mile errand run around town), extremely brief and very intermitent. Primarily affecting the low speed shifting confusion, I would notice it most frequently when accelerating in the second half of a turn. Must be the grounding in the tranny losing contact.

The brief loss of ground would therefore affect the solenoids, not directly, but via the corruption or loss of the signal(s) from either the TPS or OSS or both. So, in that sense, the TCU is involved.

Lastly, I am very confused about the testing of solenoid 3. I may retest everything at the connector next to the dipstick. As indicated, the new ground only "improved" the lockup problem but the toggled wire around the TCU continues to work. The final solution there will probably be a new TPS or OSS.

Have you dropped the pan on the AW4, and checked the solenoids directly to see if solenoid #3's ground and physical lock down bolt are loose? That one bolt seals the solenoid Tfluid flow, and grounds the solenoid to the T case. Also there is a push on connector that delivers the 12 volts to the solenoid, it could be loose.

 

[Ecomike]

Finally got around to changing out the TPS. No change in lockup problem.

Have you check the wiring harness ground at the TPS, Pin A, I guess? (check the manual) To see if the ground is less than one ohm? Test must be run from the battery negative post to pin A on the harness, with the TPS disconnected.