Auto Gearbox Issues.

[Pentagram]

Hey I've seen some other posts with the same issues but non of them have an ending so I don't know what they did to solve the problem.

Cruising on motorway in 5th without any warnings it lost drive. Pulled over, checked oil and dipstick was near max. Turned car off/on, started driving 1st and 2nd gear are fine went into 3rd and lost drive after 4-5 seconds in gear. Drove it in 2nd for 15miles to my appointment and got it recovered home. Had no signs before hand. Put about 1l of ATF in when it got home. Unplugged battery, ran codes and only got 1(65). Left it sat for like a week or 2, took it for a quick spin round the block to see if any new codes came up after driving and got (43). While driving it went into 3rd and had drive, went into 4th and had drive for 4-5 seconds and then lost drive in both 3rd and 4th.

1st, 2nd and reverse work fine.

Codes
43: 3 speed complete control of transmission
65: APS system, or TPS

I was about to buy a new gearbox but saw someone else that had this issue and they replaced their gearbox and it didn't solve anything.

[Amonlym]

Everything below is based on looking at the ATSG F5A51 manual which i am assuming is closely enough related to W5A51 to be relevant. I otherwise know little to nothing, so... Good Luck

Based on the symptoms 1,2 ok, 3,4,5 not ok points to an issue with overdrive clutch or related parts. The OD solenoid is turned OFF for gears 3,4,5. Middle solenoid, side nearest the screw on filter.

If swapping box doesn't fix it, then I guess either a short to live on the signal to that solenoid, or, a failed high driver in TCU. If swapping box did fix it, its a stuffed solenoid.

Normal impedance 2.7-3.4 ohms @ 20c for the solenoid, terminals 9 and 5 are that solenoid.

Loom connector: with 6 connections to the bottom and 4 to the top, the numbering is:
7,8,9,10
1,2,3,4,5,6 (left to right both rows)

looking at case you have:
10,9,8,7
6,5,4,3,2,1 (left to right both rows)

Best of luck!