A4LD Torque converter or engine issue ?

[IIBRONCOS]

I have a 1988 Bronco II with the A4LD automatic transmission and 47,000 orig miles and sat for 12 years.
The transmission shifts great from 1-2-3-4 but acts erratic at torque converter lock-up. Sometimes the TC will lock-up and stay locked up as long as it needs. Other times it will rapidly kick in and out of Lock-up even on a level or slightly downhill road. I talked to a transmission shop today and they said it did not sound like a transmission issue but and engine issue, like a sensor, brake light switch or an RF signal picked up by the computer. The engine runs great and I don't get any CEL. The transmission has no leaks and the fluid is full and very clean. Can someone help clarify ?
Thanks.

 

[Mackhedq]

I have a 1988 Bronco II with the A4LD automatic transmission and 47,000 orig miles and sat for 12 years.
The transmission shifts great from 1-2-3-4 but acts erratic at torque converter lock-up. Sometimes the TC will lock-up and stay locked up as long as it needs. Other times it will rapidly kick in and out of Lock-up even on a level or slightly downhill road. I talked to a transmission shop today and they said it did not sound like a transmission issue but and engine issue, like a sensor, brake light switch or an RF signal picked up by the computer. The engine runs great and I don't get any CEL. The transmission has no leaks and the fluid is full and very clean. Can someone help clarify ?
Thanks.

Did you ever figure anything out with this? Mines basically the same way, just all over the place for no reason.

 

[racsan]

I just read another post with lockup tc issues and there was talk about a possible bad temperature sensor. Check for codes, I personally dont know much about automatics , have read some posts on a exploder forum about a “brown wire mod” where you apparently tap into the wire that controls lockup (must be brown, lol) and you can manually lock the converter for better fuel economy. just remember to switch off or youll most likely stall the engine when you come to a stop.

 

[lil_Blue_Ford]

CEL doesn’t have to light to have codes set on OBD1, and often a TC code won’t appear anyway. I had an 89 Bronco II that had no TC lockup. I used it as a campus beater so it wasn’t a major issue, but eventually I went looking for it. Turns out the transmission wires ended up against the exhaust and melted.

Vacuum leaks and bad TC solenoid can cause havoc too.

 

[IIBRONCOS]

Did you ever figure anything out with this? Mines basically the same way, just all over the place for no reason.

I took it to a reputable transmission shop and they did a complete rebuild. They told me from sitting the rubber parts were stiff and not sealing properly. The new kit has better seal designs also. I haven't had any problems since. Hardened up rubber seal in the transmission was preventing reverse from engaging The new seal has 2 lips for better sealing. If you get it rebuilt make sure they do a complete rebuild, not just a soft parts rebuild. Specify a Ford front pump. New converter etc. Sorry for the late reply. The A4LD is often criticized, but so many of these transmissions were/are abused by off roading, high temperature and shade tree fixes. Make sure you have a cooler for the transmission.