Fuse/Power Supply for Electric 4x4 (87 BII)

[CraigK]

I've posted on the main forums in the "4WD Systems" section, but am not getting any help on this specific question.

The vehicle is an 1987 Bronco II with electric pushbutton 4x4/LOW control. I have no power to my T-case controller. (I have already replaced the T-Case motor.) I do not get any clicking when I push the 4x4 or LOW buttons, and have no red light on (blinking or steady) on the controller itself when I run the diagnostic. There does not seem to be any power supply to the controller.

I cannot figure out which fuse or fusable link or whatever is supplying power to the t-case controller. I doubt it is the 5A fuse in the #17 position of the underdash fuse panel, as the amperage requirement should be 15A or 20A. I have no under-the-hood power distribution box (that I can see).

Does anyone know what fuse/wire provides power to the t-case controller on this year of BII with electric pushbutton control???
Thanks.

CraigK

 

[unoleisu]

*The fuse for the Electronic shift control module is #6, a 15 amp light blue fuse.
*On the BK/W wire there is a fuseable link "P" it is 20 GA RED it is down line of Connector C177 which is near the HEADLAMPS. Fuseable link "P" is at the starter relay, near the battery.
* W/P wire is the one that goes from Fuse thru Connector C144 to the ESCM. Connector C144 is located at 4x4 transfercase control.
*The Black wire is ground and passes through C144 as well, has a splice in it (S200 Center of Instrument Panel near blower switch takeoff) and grounds at G200 behind I/P to left of steering column.

I would start with the fuse, look at Fuseable link next, check ground, then start looking at connectors. Hope this was helpful.

 

[4.0B2]

You say there does not seem to be power on the overhead console? Not trying to be a jerk, but have you checked?

 

[unoleisu]

The roof console wireing goes thru the Electronic Shift Control Module. Although there is a LB/R wire that comes from Fuse #17, a 5 amp tan fuse for instrument lighting and lamp out warning. There is a connector C169 in this circuit, not sure of it's location.

 

[toddhamby]

Did you ever figure out your 4x4 problem? I'm have the same issues. Thanks Todd

 

[CraigK]

Yes.

I thought it was a bad module, but the used replacement I picked up did the same (no light). I went back and tested the connectors going into the control unit again (as per the directions in the Tech section). This time I noticed a power drop (below 12V) on the power lead that I hadn't seen before. Power also seemed to be intermittent, sometimes powered sometimes not. So I just cut the power supply wire a few inches from the connector and ran a new 12V line to that wire/pin. Instantly fixed. LED came on, shifts A-OK.
Hope this helps.

CraigK

 

[toddhamby]

Thanks. I'll check it out this weekend.

 

[Kmh2003]

Hey guys, I am new to the forum and am looking for some help with my 87 B2. I am having the issues with my electronic shift 4x4. I have a book and have looked over the schematics but can't seem to figure anything out. I tried the whole thing stated earlier in this thred but can't seem to find anything. I need some help if someone could guide me. Thanks yall