I have a 1990 bII that has been running fine for the last few months. After a week of sitting in the driveway the bronco now has a few problems:
1 - tachometer no longer functions (comes a little off zero when started but no other movement)
2 - door chime will not shut off, I know the door switch works as the dome light comes on and off.
3 - the bronco was parked with 4x4 and low-range off, now 4x4 and low range are engaged and I can not un-engage them. The low-range light only blinks when pressed, then goes solid again once the clutch or a gear is engaged.

The week the bronco sat in the driveway we had a few nights of intense lighting storms, could this be the result of an electrical current from lightning? All other electrical systems still function as normal.

 

Welcome to FTE!!!

I would start by pulling the codes, I have a link in the tech info thread on pulling the eec-iv codes.

 

I know this sounds a little dumb.. but are you really stuck in 4low, or is it just the light staying on? You will definately know the second you start going if you are or not. Just asking that because you didnt mention if you actually drove it at all or not.
about the tach and the door chime, couldnt help you there buddy. sorry. But honestly it sounds like you just have some goofy electrical gremlin. Most likely it'll be a pain and a half to find it, but cake to fix it once you do. let me know what you find out.

 

Yes I have driven it up and down the driveway, and its definitly in 4low. I tried pulling the codes but the digital meter I have is a little slow, ill have to go get an analog meter today. I had an electrical gremlin last year and finally found that the main cpu had water damage, I replaced it and the bronco has been running great ever since.

 

I'm assuming you have the pushbutton 4 wheel drive since lightning would have no effect on a mechnical system. Are the indicator lights on? Do you hear the relays click when you push the buttons? Have you pulled the fuse to the 4x4 system and then reinstalled the fuse and tried the system again? You mention previous water damage with the CPU, and these problems could also be from the first occurance, just took longer to show up. How much water are we talking with the original water damage? You can also try unpluging the wire harnes from the transfer case and try to recycle the pushbutton controller. Pull the battery cable off and reinstall after 20 seconds or so and see what happens.

Good luck!

 

The codes from the KOEO test are 11 and 11 (i think), here is the pulse output:
pulse - 2s - pulse - 4s - pulse - 2s - pulse - 9s - pulse - 6s - pulse - 2s - pulse - 4s - pulse - 2s - pulse - end

seems like the 9s pause should only be 6s but close enough? I have not done the KOER test, does any one think I should?

I have disconnected the battery and left it for a few minutes, reconnect and problem is the same. Also pulled the 4x4 system 40A fuse and then reinstalled with no change. I did drive it around the block today and everything seems fine except that its stuck in 4L, the tach doesnt work, and the damn door chime never shuts off!

I have tried listening for any relay clicks or motor noise when pressing the 4x4 and low range buttons but I cannot hear anything. Possible I wont hear over the engine noise or perhaps the motor is not even trying to run..

I am wondering how the 4x4 and low range buttons are supposed to function. I have never actually used the low-range before, but I know the 4x4 used to turn on and off as expected, cant remember if it acutally flashed while engaging/disengaging. is the low range supposed to act the same? And will the 4x4 not even attempt to disengage if the low range is still engaged?

I am starting to think that some unknown event (lightning?) caused an electrical pulse through the system causing the tach to fail, door chime stuck on, and the low range motor to engaged and then die.

Any other thoughts?

BroncII - The water damage was a small leak from somewhere up above the cpu. Salt water (from michigan winter driving) had dripped down and corroded some of the cpu components. I was suprised it worked at all! I replaced the entire cpu with another used and have had no problems untill now (6 months of driving). I dont belive this to have been a problem all along and only show now, but then who knows...

 

On the electronic shift system, you must be in Park or Neutral to shift in and out of low range. You should hear the relays cycle as the system engages, I was looking for a diagram tonight, but couldn't put my hands on it. My door chime (87) is located behind the glove box, if you want to pull the connector off until you figure out what the problem is, it may keep you from going nuts! I will keep looking, you may have a ground that has come loose or a bad relay. If the truck was hit by lightning while the truck was running and in 4 lo, I could see maybe that it could get stuck in that position, but if the truck was turned off, I don't see how it could "put" the truck into 4 lo mode. Should be interesting to see what the cause is. Get the volt meter out and see what power you have up at the electronic push buttons and then down at the relays.......gotta find a diagram that shows how the tach is powered to see if there is a comon thread here...


Good luck!