Four wheel drive not engaging, the torque on demand system is not working

1999 ISUZU TROOPER

204,648 MILES • 3.5L • V6 • 4WD • AUTOMATIC

BULLDAWG1978

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When I push the auto 4x4 button the "4hi" does not engage make any kind of sounds what so ever. I can manually put it in 4lo with no issues 4lo works as it should.

Any help would be greatly appreciated thank you!

Mar 5, 2017 at 6:49 PM

KASEKENNY

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18,907 POSTS

This could be a couple things but we need to start with checking for codes. Here is a guide that will help with this:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

However, I suspect you have an issue with the clutch or engagement system. I attached the info on this below.

We need to find out what the display in the cluster is showing you when this is not engaging. It should show the current status and any errors if there are any.

Please see the attached information and we can start working through this. Thanks

Images (Click to enlarge)

Dec 27, 2020 at 3:58 PM

DANNY L

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5,648 POSTS

Hello, I'm Danny.

The tod- Torque On Demand is controlled by the ECU and should show any fault codes on the instrument panel. I've attached picture steps below showing tod theory and the tod ECU replacement. I would have it checked for proper function. Hope this helps and thanks for using 2CarPros.

Images (Click to enlarge)

Dec 27, 2020 at 4:15 PM