Isuzu bighorn with TOD - what's the deal with this?

[mudgrip4]

Seems TOD (torque on demand) appeared late 96 through 97 for 3.1s.

From reading it sounds like an early traction aid setup - a dozen sensors relaying information to cause traction balance to alter from back to front etc as road conditions require. At first glance this sounds like a dozen additional reasons for things to go wrong in mud and rivers.. and TOD does appear to cause some problems esp at this age.

How does this thing work - can it be left OFF permanently so you have normal transfer case operation plus hopefully LSD in rear. Can it be removed? Asking because may buy another 3.1 if I can find v clean one under 200kms - odd ones around. And there's a 96 TOD truck on trademe at present with 159ks on it..

Thanks Mike

[geeves]

tod in a 96 Unlikely. It will probably have push button 4wd and the diff with the dog clutch and no freewheel hubs. It is correctly called shift on the fly. They are the same bits the tod uses except for the computer

[mudgrip4]

Hi Geeves - its on trademe as a 96 3.1, 159ks, Oamaru.

Looking it up on carjam its still specced as 96. My last bighorn was a 96 and non TOD - so thinking late 96 and 97 variants have this. Discussion on isuzu 4x4 Fb site now - says there are mods you can make to circumvent this system. My last biggie was a fine truck but had an ongoing electrical gremlin - I do not want another problem in what is otherwise a fine old truck!

One article said 12 sensors involved in operating this TOD (diffs/box etc) and in 27 year old offroad (rivers and mud etc) truck that's 12 more things that can go wrong. Prefer to avoid TOD but this truck just 159ks - alot of good miles in it..

[geeves]

Good question. Dash clearly has the tod display but a not very quick search suggests tod was introduced in 98. As it was imported in 2017 its possible the model year has been entered wrong but only an inspection in person will solve that. Look at the NZ vin number on the plate and rear window, the chassis number on the plate and the chassis. Add the usual checks and see how you go. Build year should also be on the firewall plate but might be in Japanese

[mudgrip4]

Overseas sites reporting TOD as early as 95?? Doesn't make alot of sense!

I think I'll pass on this one because long way south to view it in Oamaru, and even at just 159ks am not interested in a risky setup. Dam!

[geeves]

tod does not work in low range. If tod fails it defaults to 2wd. You dont have a lot that is going to strand you just west of central nowhere.
Oamaru is only 2 1/2 hours each way

[mudgrip4]

Aaaahh!! For sure 159ks in a very tidy 3.1 has pluses. Alot of truck for the money as you also know. Excellent ride, quite good diesel, gearbox/transfer case good for 315ks in my last one, very strong drivetrain, and very good LSD if G80.

But.. my last truck gave intermittent but continuous electrical problems. Blowing fuses, popping warning lights we could not properly code - all sorts of electrical bother. I don't want a bar of that. I'll show the Isuzu 4x4 Fb discussion to experienced mechanic mate for an opinion... Yes TOD only works in Hi 2WD but what happens when it begins to short/breakdown - which it will after few immersions in Waipara River, or unavoidable bath in mudhole on the Old Man Range or similar.. And those 12 TOD sensors will have a lifespan - well due for maintenance/replacement after 27 years anyway (1996-2023).