Isuzu Trooper Owners Club UK™

[steviebax]

First off you need to see if you have vacuum.

Have a look under the front drive axle on the passenger side. If l've inserted this piccy correctly in this post hopefully you will see something that looks like the picture.

You need to start the engine and let it run for a while then you need to take one of the pipes off the valve looking thing in the piccy and see if you have vacuum to it.  You will more than likely hear the suction in the pipe or you can either put your finger on the end of the pipe.

Check each pipe at a time you should have vacuum on one of them and when you press the 4x4 button the vacuum should switch to the other pipe.

If you have vacuum in either of the pipes than thats good.  

If the vacuum is not switching from one pipe to the other when you press the 4x4 button then you need to start checking the vac pipes.



Email me back with what you find out and we'll take it from there.

One step at a time.

Steve

[Google]

[mattysbantam]

i have no light at all when i press the 4wd button is ther a fuse or bulb just bort the trooper so any help thanks

[dennis52]

Great information on this thread and I am now getting my head around the SOTF system. However I still need to understand why SOTF relies on vacumn hoses to operate the piston that moves the fork in the front actuator. Couldn't this be done only using solenoids ? What am I missing?

[TrooperSimon]

sorry guys just moving this post back up the ladder

it so good at explaining system for afew folk i hav been trying to explain it to

cheers

simon

[Rhanagar]

Sticky maybe
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[Rhanagar]

oops ... it is already ... too early for cognitive thought processes.
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[slimjim]

hi if anyone can help I have a 98 Vauxhall Monterey 3.1td manual it has a gearstick to engage 4wd not button the transfer box is engaging and the little prop is spinning when I put it in 4wd I have no light on the dash front wheels are not engaging I have read through a lot of posts on here I don't seem to have any vacuum at the front actuator whatsoever I cant seem to find the main feed for the vacuum the one on the chassis I have pulled the pipe off and have nothing from either end I have cleaned out the valves on the front as they were blocked solid when I put it into 4wd the relay under the bonnet is clicking but I have no vacuum I think this is the problem thanks

[champ]

So what does it mean please when the green flashing on the dash shows "check" in red?

[Countryguy]

Hello All,

First time poster and hope you can help.  I've been working through the various posts and especially Rhanagers fantastic piece of work on the SOTF system but still no luck.  

Here's the lowdown:

In the beginning it just wouldn't go into 4wd and the indicator light flashed quickly.

Starting at the back the rear actuator was clunking away fine. The transfer switch was registering correctly in terms of continuity under the gear levers, the vacuum at the axle mounted VSVs wasn't switching and the front axle actuator not moving.  I took off the valves (carefully checking and labelling) and also removed the front actuator.  The blue VSV was seized and is now replaced. The electric supply to both valves measures 12v when in 2wd. The front actuator has also been replaced and fingers crossed I pressed the switch and hoped. Hey presto, into 4wd and steady light on the dash. Press the switch again, slow flash followed by rapid flash and won't come out of 4wd. In frustration, I took it to a main Isuzu dealer who after taking £207 suggested that it was the 4wd ECU, helpfully the suggested trying a second hand unit as a new one is £350 but as they didn't have one in stock they couldn't test it. So I've now fitted the replacement 4wd ECU and you've guessed it, still the same.  

I've double checked everything and you would think it was the switch on the front actuator but this is working fine and has the correct washer in place. If I manually disconnect the transfer switch, the power goes to the VSVs and the actuator moves and it's back in 2wd, but connect it again and it's straight back into 4wd. I though this suggested a stuck switch but it checks out fine.  Starting from scratch, it seems now when pressing the magic 4wd button, there is no clunk at the rear and the rear actuator seems not to be doing anything.  I'm struggling to test at the plug if a supply should go to this or not when pressed but the plugs are all clean and connected properly, just no noise so I reckon it's stuck somehow, not sure how easy this is to replace.

I've changed all the vacuum hoses just for completeness, but just seem to be going round in circles.  

Any help would be so much appreciated as not mad keen to go back to the dealer and the snow is already falling here.

[Rhanagar]

I would say you have an electrical short somewhere on the front switch wiring. Possibly a bad earth.
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[eithan h]

try a different 4wd motor on the transfer box, if you even pull the plug apart it alters the readings from the ecu on the wires going to the motor and nothing on the 4wd system will work. it is quite an integral part of the system and everything else is triggered by it

[Countryguy]

Thanks for the replies, much appreciated.  Checked all the earths I could find and examined the cables and sadly can't find anything wrong, cleaned everything and resecured to be safe but still the same issue so will follow eithan h suggestion and try to source a new motor on the transfer case. It doesn't make a sound at all either way at the moment so I'm hoping this could be it, parts need to be sourced online up here so fingers crossed, just about everything else has been replaced!

Again, appreciated and will report back.......

[Countryguy]

Folks, thanks to this forum I have a fix. The rear actuator was indeed faulty, despite having worked at the start of the troubleshooting. That's almost the whole system replaced but thankfully now switching happily between modes. Most grateful to all.

[Skylo]

Thanks to Rhanagar for a great post, wish I found this before I spent hours on my back and saved some cash.Following the steps it looks as if my actuator is stuck.Before I start looking for a replacement I want to try and make sure the actuator has enough oil in it.Does anybody know if the fill is the bolt with the hex key? The service manual does not have a expantion diagram of the actuator.Thanks

[Rhanagar]

Bolt 17 in the lower right of the picture.

This is for a B Series Frontera, but it uses the same system. If it is goosed then an actuator off the B Series Frontera will fit and work just as well, if you cannot find one off a Trooper/Bighorn. These actuators fail to the rubber diaphragm splitting inside. If you remove it and try the 4wd button you might see it move. Its only when the actuator is in place and under load will the vacuum be not strong enough to shift as the vacuum slips past the split in the rubber. When free sometimes the forks move giving false impressions.
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS