WHY DOESN'T TRANY SHIFT WHEN IN 4 LOW

Reply Subscribe

Thread Tools

Search this Thread

Jul 11, 2016 | 04:26 PM

jkmra5

Thread Starter

New User

Joined: Jul 2016

Posts: 4

Likes: 0

WHY DOESN'T TRANY SHIFT WHEN IN 4 LOW

I converted a 1992 F-250 from 2 wheel drive to 4-wheel drive.
The donor truck was a 1991.

Everything seems to work but transmission will not shift when in 4-low.

What did I miss???

Jul 11, 2016 | 04:51 PM

Festus Hagen

Methanoholic

Joined: Mar 2009

Posts: 6,442

Likes: 8

From: Maine (NorCal Native)

I suspect the 92 uses the VSS in the rear end, I suspect the E4OD believes it's going to slow to shift.

What to do about it, I'll leave that up to the folks that know these trucks much better than I ...

-Enjoy
fh : )_~

Jul 11, 2016 | 07:58 PM

Conanski

FTE Legend

Joined: Jun 2006

Posts: 31,930

Likes: 1,499

From: Ottawa, Ontario

There is a range switch on the t-case that is supposed to connect to the PCM to tell it when low range is engaged, but I don't believe a 2wd PCM has an input for the range switch so...

Jul 11, 2016 | 09:12 PM

jkmra5

Thread Starter

New User

Joined: Jul 2016

Posts: 4

Likes: 0

I was able to plug in the wiring harness from the transfer case to the 92's wiring harness.

Checked on part #'s (12B565) for the controller and Ford is showing the same one for 2 wheel drive and 4 wheel drive for both 91 & 92 model years

Jul 12, 2016 | 01:41 AM

GuitarJesus

Posting Guru

Joined: Apr 2012

Posts: 1,693

Likes: 3

From: Menifee, CA

Quote:

Originally Posted by Conanski

There is a range switch on the t-case that is supposed to connect to the PCM to tell it when low range is engaged, but I don't believe a 2wd PCM has an input for the range switch so...

PCM is the same for 2wd or 4wd

Jul 12, 2016 | 09:12 AM

Lead Head

Lead Driver

Joined: Jul 2007

Posts: 7,868

Likes: 9

From: Rhode Island

For whatever reason, the 4-low input switch is not telling the PCM you are in 4-low. Does your 4-low dashboard light turn on?

Jul 12, 2016 | 09:40 AM

jkmra5

Thread Starter

New User

Joined: Jul 2016

Posts: 4

Likes: 0

No the dash does not light up for 4 wheel drive or 4 Low.

Since this is a 2 wheel dash would it have the lights to do so?

Jul 12, 2016 | 11:26 AM

Briansshop

Fleet Mechanic

Joined: Aug 2005

Posts: 1,277

Likes: 89

From: MD

My 2wd 350 had wiring for the t case sensor. Lights in dash,all there.

Jul 14, 2016 | 05:49 PM

#10

jkmra5

Thread Starter

New User

Joined: Jul 2016

Posts: 4

Likes: 0

Fixed it!!! with a different (1995) transfer case wire harness.

1991 transfer case wire harness uses a different port to send the LOW/HIGH indicator message on than the 92 does. This is because the 91 has a extra VSS on the Transfer case.