Hi guys just curious as to whats going on with the 4 speed in my EF. When cruising on the highway it will often drop down a gear & have the car revving at 4k then drop back into top gear, it does this quite often. Tonight I was rattled as it would suddenly have no drive at all and the car would just be free revving, i'd slow down park then take off again and all is well for a while then this circus starts again and continues at random intervals. Is the box stuffed or more likely something smaller? It's a change over box with unknown km's, I've never been happy with it as it is no where near as slick as the original unit...

check the fluid level, this is exactly what they do when low on fluid, you may have a leak aswell, check the rear seal where the tail shaft goes into the gearbox

Inhibitor switches fail and cause erratic behaviour, mine would drop down 2 gears with the cruise on for no reason, then it would go back to normal.

Thanks for your help guys, I'll just get the thing serviced. Drove it today and it was smooth as silk, so it's definitely a random thing!

Just to add a few notes regarding my experience with the BTR gearbox inhibit switch, albeit on an AU.

Initially the inhibit switch began to fail and would only allow a start in neutral, not park. Laterly the gearbox operation became erratic. After a cold start the gearbox was fine (shifting up and down) I could join the freeway and acclerate upto 100km/hr. The gearbox would change up and I'd get torque converter lock (about 1,800rpm at 100km/hr). Then after 10km the revs would suddenly climb to about 3,000. After leaving the freeway and stopping at traffic lights the gearbox no longer changed up as normal. My assumption is the ECU had entered limp home mode and thereby set the gearbox to a fixed third gear (from standstill to full speed). The torque converter was thereby providing all "gearing". When this happened I used my scan tool, this yielded P0753 error code -shift solenoid No.1 fault. My first plan was to follow the code and drop the gearbox pan. However this didn't seem right. Then I remembered that the inhibit switch provide gear selection information to the ECU. As the switch was already faulty I decided to replace it. This I've done and have just completed 500km of trouble free driving. During the removal of the switch (I'm lead to believe they often break when being removed) I discovered the cause, see attached photo. Within the switch are a number of resistors, associated circuit board segments and a wiper. The gear selector shaft moves the wiper and in so doing the relavant resistor is switched into circuit. The ECU then "reads" this resistance and thereby the selected gear. In my case as the inhibit switch broke down black carbon like deposits (I'm guessing from arcing) where formed. These then bridged the segments causing an erroneous resistance value. Im guessing the ECU "knows" what gear the gearbox is in but the feedback from the switch doesn't match and to protect the gearbox limp home mode is selected. Although I know you're ECU is different I'm wondering if your switch is providing similar erroneous signals. As an aside I was warned that the gear select shafts that operate the switch corrode quite badly (sometimes snapping). This was definately true in my case. I think the worst piece of corrosion on the vehicle is this small selector shaft!

Hope this is of help!

 

 

Attachments:

BTR gearbox inhibit switch.JPG [ 324.12 KiB | Viewed 270 times ]

Thanks for the info mate. By the sounds there seems to be a number of things that can cause the gearbox to act up.

Hi just had to give my imput I have a el auto has done around 400 000 km so I dropped the pan and gave it a good service surprising there was stuff all metal bits in pan.. Then auto kept going into safe mode So I changed the inhibitor switch and also the TPS then reset the ecu reset the TPS according to the Gregorys manual (better than ellerys) Have a car now thats done 1.195.000 kms and like a new one thanks for the assistance

older thred but im bored .
check the trans fluid, the metal fluid pipes wear on the sump in older vehicles.mine anyway.
as previously said check the magnet on the transpan for metal.
source a second hand gearbox cause if its slippin it prolly needs replacing or reco