Engine/Transmission (1994 - 1998) transmission problems

[mullady76]

I've got about 60k on my BD transmission. Now I am have some problems with it. When it shifts from 3rd gear into 4th, the transmission drops back down to 3rd gear for a second or two, then shifts into 4th and locks up quickly. Everything else seems fine, no slipping or any other problems. What is causing this and is it going to be expensive?

 

[Boldt's Wagon]

Ask Bill at:



http://www.dieseltrans.com/phpBB/index.php

 

[chrleb1]

What it might be is that your torque converter is unlocking for the shift into overdrive and locks back up after in overdrive. Just an idea, not quite sure though. Its hard to diagnose these things without riding in the truck.

 

[Ben Rumson]

Could be your overdrive fighting with your Throttle Position Sensor.



If this happens it will drop a gear and then jump right back very abruptly!



This is more pron to happen with the OverDrive "active". Try disengaging your OD at the same stretch of road and see if this prevents this from happening. If it does, then I'd say it was your OD and TPS battling it out. OD wins first round, TPS drops a gear suddenly in round two, and then the OD comes around to win round three.



Best solution is to know about when this happens and disengage your OD for that stretch of road, if possible, so the two dogs won't fight.



Mine used to do this just below the same mountain summit while the OD was active. The OD thought it could handle the hill and the TPS would suddenly (and violently) drop a gear. Then in a fraction of a second, the OD would take over again.



I haven't had a problem with the new transmission and power enhancements.

 

[shendren]

first put in a mystery switch (ground the orange and black wire going to the transmission). that will determine if it's electrical or hydraulic... ... ... .

 

[mullady76]

The mystery switch is what blew my first transmission. Felt like a rocket having the transmission lock up in second gear. Posted my question over at diesel trans.com and got a quick response. Thanks Bill

 

[Reb.B]

your t/c is locking up in third gear then disengaging before it sfifts into 4th. could be junk in the valve body. couple other things could make it do the same. Almost all of them stem from the valve body.