Not sure what's going on, when in 2 wheel, the back two wheels on the indicator are flashing (twice a second) and after a minute the CHECK light on the TOD display flashes. The car runs fine and TOD and 4WL both engage and work. So I ran the codes for TOD (jumping pin eight) and I get code 12 which indicates it is running normally. I then reset the TOD computer, thinking it may have been storing that error from a previous fault. It reset fine, but the reaer wheels are still flashing. The indicator lights perform normally in TOD and 4WL.
Am I correct to assume that whatever sends the signal to the display to indicate what state the axles are in is simply not sending the right signal or can't determine it's state?

 

Apparently didn't wait long enough for the code, I didn't know it flashes 12 three times before the real code.
So it's actually Code 28 - ADC (+) & AXLE SW Output abnormality

I got the Workshop manual, and according to the workflow the first step is to check for voltage between terminals 5 and 19...

5 and 19 on what?... I can't find an image of the ECU for the life of me and the only thing under my seat looks like a stereo amp and has way to many terminals according to the manual.

 

Although I never checked the codes, I just had these identical problems on my 2000 Trooper.

I just had the intake manifold gasket replaced for the 3rd time (last time was just 15 months ago). When I went to pick it up from the mechanic, I started the car and immediately noticed the flashing rear wheels on the TOD indicator (the car was in normal 2H operating mode). I went straight back in to the mechanic, and he was at a loss... I left.

On the way back to work, the "check" light under the TOD indicator started flashing red. A friend and I popped the hood, and luckily he saw a vacuum line that had come loose (probably during the intake manifold gasket job), popped it back on, and everything immediately returned to normal. The vacuum line was at the very back of the engine bay, up high, driver's side, maybe a foot off of the vehicle centerline.

Hopefully this saves somebody a trip to the shop and a couple of bucks.

 

oh dude... really?

Can you snap a pic of the vacuum line in question.

I kinda just abandoned trying to fix it as the only symptom is just a flashing light. The vehicle handled our rather heavy winter both in TOD mode and Low 4, so i'm not woried that anything is mechanically wrong. i'd love to try your fix, don't know what i'd do without my little flashing friend on the on the dash everyday though

 

I drove our other car in this morning, but I'll try to get a pic posted soon. There are some small diameter (1/4"? 3/8" maybe?) black rubber lines on the drivers side of the engine (near where the injectors are). If I remember right, they join at a "T", right there on the side of the engine. Follow each of those lines to wherever they go and just make sure that all hook up securely to some fitting. Also, I'm guessing a small crack or leak in any of these lines could cause the same issue... so you'll need to look at them all closely.

Just driving the 7 miles from the shop to work with the flashing lights was so annoying that I turned on the TOD on dry roads just to make it stop! Hope you're able to find and fix this problem as easily as I did.

I tell ya, I've got about 135k miles on this car, and have had it since 60k. I can't wait til I can afford to get rid of it. It's needed so many repairs over the last couple of years... most unreliable peice of s I've ever owned. And I've taken good care of it, too!

Good luck.

 

I'm really glad you posted this - saved me a lot of time! Same symptoms and same cause in my 2002. In my case, the hose had been eaten through by a packrat. In the attached photo, the hose is running left to right starting at the tee connector near the intake manifold. The white electrical tape above the hose is protecting a repair where a previous packrat had chewed through the injector connector.

Not sure if the picture will actually be useful, the upload limits it to 95K!

 

Stupid rats. Glad the info helped!

 

Forgot to mention that mine was showing TOD codes 14, 24, and 28.