control module testing

[midnite]

Working on an 03 f250 4x4 on the fly. When turning switch nothing happens. Shift motor is good, I can control it from the relays by grounding. I replaced the 4x4 control module with a used one with same numbers but didn't work. I'm thinking that module is also bad. Is there and way to test the module to be sure. any ideas ?

[midnite]

Is there anybody out there?

[southend]

Are your vents blowing through defrost when you switch to 4x4? There is a ton of info about this in the drivetrain section.

Sent from my phone that somebody didn't help me get.

[midnite]

Haven't checked.

[southend]

Originally Posted by midnite

Haven't checked.

If so, it is likely related to a vacuum leak, with esof. Could be bad hoses, or hub seals.

Sent from my phone that somebody didn't help me get.

[midnite]

Has manual hubs

[southend]

Originally Posted by midnite

Has manual hubs

Your first post says 4x4 on the fly, are they after market hubs? Has it worked in the past?

Sent from my phone that somebody didn't help me get.

[midnite]

Yes hubs were switched. Has worked in the past.

[southend]

Sorry, i'm not familiar with the module test. I've seen quite a few threads on the drivetrain section.

Sent from my phone that somebody didn't help me get.

[sinner6.0L]

does the 4x4 light up on the instrument cluster when you put it into 4 high?