bw 1354 t-case and O/D light flash

[blue88b2]

alright, so i just got my 97 explorer on the road 2 weeks ago after reinstalling the rebuilt 5 speed automatic and some engine tuning. I got a BW1354 transfer case to go inplace of the auto one since i will be doing a sas. so everything works great, but when i put th t-case in 4x4 low after about 5 minutes of driving the Overdrive off light starts to flash on the dashboard. Which i thought meant the transmission was having serious problems. so i stop the truck put in park, turn off motor, and then turn on again. then five minutes later it's flashing again. take it out of 4x4 low, and no more flashes? what's it doing? does it hunt the tranny or shift patterns to keep driving with it flashing? I put the original speed sensor from the auto t-case into the manual one, so that cannot be it. any ideas?

 

[MrShorty]

I'm posting this as much as a question as a possible solution, because I don't really know. Here's what I'm thinking:

1) My '92 doesn't have any connection between the PCM and the transfer case to tell the PCM when it's in 4L. Where my transmission is vacuum controlled (1st -3rd gear), the PCM doesn't need to know nor does it want to know nor does it care if it's in L.
2) Your '97's transmission, on the other hand, has an all electronic transmission. In this case, I would expect that PCM wants to know and needs to know when it's in L. I'm not familiar with any of the specifics on the 2nd gen system, so I don't know how the PCM is told when it's in L.
3) My suggestion is that, when you swapped in the 13-54, you overlooked, ignored, or didn't correctly connect the L signal between the t-case and the PCM. Again, I don't know specifically if or how that needs to occur, but it seems reasonable to me, given the symptoms you describe.

 

[blue88b2]

I think you are right. Guess i just need to figure out how to get a "low range" signal to the computer? Anyone have ideas or wiring diagrams that could help? I know others have swaped in this t-case, what did they do to remidy the problem?

thanks again for the reply!

 

[Willard]

It's probably confused because the axles are spinning much slower than the transmission output shaft.

So yea, you need to figure out some way to get the low range signal to the computer. I would start by going through some of the stickies in this forum and see where that gets you.

 

[blue88b2]

does anyone know where to find a wireing diagram. I'm going to jump the wires with a switch to get the signal to the computer?

 

[IZwack]

Well I think I finally have this figured out.

The difference between the 97 and 98 4.0 v6 Explorers is that the 98 eliminates a VSS sensor on rear output of the transfer case. This is why I was able to get away swapping a BW-1354 manual transfer case into my 98 w/o getting a blinking O/D light. In your situation however, which is a 97 Explorer, swapping to a manual BW-1354 deleted the VSS sensor on the rear output of the transfer case. My guess is that the computer calculates the transmission speed and compares it to the reading from the sensor on top of the rear differential -- any difference results in a blinking that O/D light.

So to sum it up, you are getting a blinking O/D light because the of the missing sensor on the rear of the transfer case.

Now that we've diagnosed the problem, its time for you to find a solution (we like creativity so be creative!). Or you can just ignore it and say to yourself that you hardly ever use 4LO and even when you do, you're moving slow enough that you're probably staying in 1st gear and therefore do not need the O/D function of the transmission.

 

[IZwack]

Ouu another thought:

The BW-1354 has this sensor at the rear output.. its in "front" (relative to the front of the vehicle) of the rear output flange and on the driver's side. I would take the sensor from your original transfer case and install it onto the 1354 just for good measure (instead of using the one that came with the 1354).

(aww crap, this is a bit too easy -- no creativity involved in this solution)

 

[blue88b2]

only problem is... i swaped the sensors already when i put the manual in. I noticed the difference because mine didn't have a cable, so i exchanged them. I'm still thinking i need to bridge a gap with a switch when i put it in low, just don't know which wires go where. I do use low quite a bit up in the hills. i don't really want to risk hurting the tranny i just rebuilt either. I've been looking in the archives for this problem, i may be getting close!

I like what you're thinking though... about the sensor in the axle and on the t-case having to comunicate. so if i can just get the computer to recognise low range, i'll be set!

 

[blue88b2]

could i use a computer from a 98 4.0? or is it in the GEM?

 

[IZwack]

You could try, its I think hidden behind the radio somewhere -- just follow the switch on the dash.

 

[blue88b2]

nissanboy had done this swap according to his sig. wonder how he got by this problem?

Just sent him a PM

 

[blue88b2]

suppose a GEM from a 98 sploder would fix this problem and not give me lots of other problems? otherwise i have to figure out how to get the vss into the 1354.. At least that's the conclution i came to. becasue even with the 4405 motor pluged in and dash switch on 4 Low, it still has this problem. More ideas?

thanks again guys!

 

[blue88b2]

So to sum it up, you are getting a blinking O/D light because the of the missing sensor on the rear of the transfer case.

yep, exactly. how vital is the VSS on the front driveling side to this problem?