My friend has a 98.5 truck with 47re transmission. He has the BD pressure lock, upgraded valvebody & torque converter. Last year he did the TC lockup switch, like on TST website. His truck is throwing codes PO743, PO1693, PO1765 lately & the tranny keeps shifting from 4th to lockup when overdrive button is on. The more throttle you give it, the harder it shifts back & forth from 4th to lockup. What can be wrong here? I'm no auto guy & just typing what he is telling me over the phone.

 

not sure if this helps but I just had a 97 doing that and the trans shop had to swap out a module in the trans to fix it. it also didn't know what gear it wanted to pull in

 

Thats what we are thinking, maybe a shift solenoid or lockup solenoid going bad, but I'm no auto guy.

 

transducer/pressure solenoid, pressure(governor) sensor and lockup/overdrive solenoids are all on the valve body, only drop the pan to access to them! very easy to replace..
sometimes the transducer solenoid(also called governor solenoid) maybe full of soot or clogged, try with it first
here is a photo:

rob

 

Thanks man, I think we got it figured out. We wrapped the wire from the alternator to battery with aluminum foil & reset the APPS, back to normal.

 

lucky you! and what about the codes?

rob

 

I have similar issues - will try that. Thanks.

Timbo's APPS fix stopped my intermitant dead pedal problem though.

 

No codes yet & it is no longer searching between lockup. It seems fine now.

 

glad hearing this!!

 

going to have to try this.
At or about 55mph it's shifting in/out of OD. How does one know if it's the solenoid or the alt wire? If the solenoid, do you have to replace the entire valve body?

What would the alt wire have to do w/the tranny shifting? thanks!

 

Alternator noise from the brushes travels thru the harness and ends up in the computer. The computer sees the spikes and wants to lock-up, then unlocl the converter clutch.
Several different fixes are out there. One company uses a filter. This gets any other niose issues corrected too.
The others want to cut and reroute wires and leave the noise!

Most suggest to start with clean and tight grounds. ( I found the passenger ground wire at the block was loose).
You can sort of test this by wrapping the bigger wire behind the passenger battery with aluminum foil. If this cleans up the problem, then do the fix of yout choice. Mine of course is to filter the noise.
You can make your own filter if you have time and understand this.
Too big of a filter ( capacitor) will slow/interfere with lock up. Too small of course may not clean up the signal.
Here is a kit you can buy.http://dieseltrans.com

 

Thanks!
I start w/alu foil around the main alt wire. The shifting issue has just started so my guess would be the solenoid, not really the alt wire but I'll start w/the easy fix first....at least this will get rid of the A.M radio noise (who listens to am anyhow).