I was fairly sure that the actuating motor was my problem however I wasn't 100% certain. What I wanted to avoid was buying a motor and that NOT fixing my problem. This might help those with a 1987 - 1991 Full Size Bronco with a transfer case actuating motor that won't engage the 4wd on the Borg-Werner 1356.
I just bought a 1990 full size bronco. the owner told me that the 4x4 used to work but suddenly quit.
The bronco's 4x4 should have simply engaged with a touch of a button but it didn't.
See attachment at the bottom of this page for a view of the buttons.
Anyway, I pressed the 4x4 and Low Range buttons and nothing. No click, crank, clunk.
I found the transfer case and saw that there was an actuating motor bolted to the rear. Here's a good pic I found on this web site:
Along with the pic, I found forum ID 11724 very helpful. User Miesk5 and justshootme84 to provide good advice on troubleshooting.
In this picture you see that the actuating motor's cables meet at a round connector. In that connection there are 10 pins. 3 are grounds and 7 are hot. If you follow the cable to the ignition then the cable will come into the cab directly under the drivers seat.
I didn't want to start throwing money at the problem so I had to troubleshoot as best as I could. I started by checking the electrical current going to the motor. I never really used a electrical tester but surfed around to get the basic handle on which setting to use. I first had to find the grounds. Then I had to find the hot wires. To find the grounds I cleaned off a part on the frame (dirt and dust) and put one wand on the frame. Next I set the tester to the CONTINUITY setting and place the other wand in each hole. When I heard the audible tone I knew that those were the grounds.
Anyway, the three ground holes (if you think of the connector as a clock face) are at the 11 & 1 o'clock position and the third is the center hole.
After knowing which holes were hot and which were grounds I could put a wand in each and test for volts.
One wand went into the center hole (ground) and the other wand I marched around the connector. With the bronco's engine running I had my son in the cab and pushing the 4x4 button on my command.
I can't remember which holes provided me with voltage but my meter would constantly read .8-1.2 volts. When my son pressed the 4x4 buttons the volts would jump to 5-6 volts but not every hole gave me a reading.
I thought I would be looking for 12 volts (automobile, right?). I'm not saying that the volt readings I got were what they were supposed to be but at this point I thought that the chances that the actuating motor was bad had just doubled. I was getting a spike when the button was pressed. At this point I was ready to take a chance at buying the actuating motor.
After calling around I found that many shops have to order the part and it would take 2-3 days. Prices range from $68 (Ebay) -$170 (4x4 specialty shop)
The junk yard was probably littered with these motors. I took with me to the junk yard my 10mm ratchet, 10 inch ratchet extension and snips. Unbolting the motor from the transfer case is a total snap. there is a total of 6-10mm bolts.
If you look closely at the web link above again you can barely make out 3 bare wires (blue, green and brown) that attach to the transfer case. To remove those wires you can EITHER remove the drive shaft and the rear case off the transfer case OR simply snip the 3 wires close to the case, giving you about 4 inches of wire.
At home I had a box of wire connectors/splicer. I crawled under the bronco with the part and the connectors and tools. Before bolting up the part I made note of the position the motor was in, I connected the plug 10 pin plug- spliced the 3 wires I snipped, crawled in the cab and pressed the 4x4 button. I heard a single click coming from under the passenger side dash. I crawled under the bronco and saw that the motor had turned. I bolted the part up- hit the 4x4 button and I was in the snow spinning both rear and front wheels.
Key words and phrases:
Bronco four wheel drive won't engage. 1990 Bronco full size 4x4 doesn't work. Automatic 4wd won't go into gear. 1987. 1988. 1989. 1990. 1991. Borg-Werner 1356. Borg Werner.
Edited by Casey.can.do, 24 February 2008 - 07:18 AM.