Auto Gearbox Problems

Some topics come up again and again. Here you will find short cuts to frequently asked questions, mainly of a technical nature.
User avatar
Supreme Being
Posts: 5115
Joined: Wed Jun 09, 2004 2:47 pm
Location: Bongo Mission Control

Auto Gearbox Problems

Post by Ian » Tue Feb 20, 2018 12:43 pm

Here's some wise advice from "Northern Bongolow":-

Not all gearbox problems are actually gearbox problems at all. The most obvious thing to check is that the transmission fluid is OK. If it smells like toast it needs replacing. Assuming it's not that, then lots of things affect when the gearbox changes. It could be any of these: fuel filter, banjo filter in the top of the fuel pump, throttle position sensor worn or out of adjustment or corroded wiring, turbo pipework leaks, all can fool the gearbox into conflict.

Cheap things I would try are

a) clean out the fuel system and run the best quality fuel you can afford, maybe with an additive in it.
b) remove the crank shaft sensor at the front of the engine, one bolt, clean its face and remove oil that collects behind in the socket, this helps the ECU tell the gearbox ecu what gear is needed.
c) check the plug wiring on the driver side side of the gearbox. Both this and the crank sensor above are prone to weather so need to be cleaned occasionally.

There's some useful information about the Throttle Position Sensor (TPS) here: viewtopic.php?f=3&t=18421

You can purchase a new TPS for pre-99 Bongos from here: ... or-pre-99/

There are fact sheets about the Automatic Transmission Fluid (ATF), Auto Gearbox Components, Auto Box Trouble Shooting, and a list of recommended Gearbox specialists in the members area of the main website : ... cts/#facts
668. The Neighbour of The Beast.