4x4 issue
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5th Gear
Joined: Nov 2024
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4x4 issue
I have tried to search through forums to try and problem solve my issue however, I’m not seeing any with my current issue. I have a 99 ford f250 sd 7.3l
When I try to activate my ESOF switch inside the cabin I don’t get any actuation from the transfer case motor or vacuum pump kick on.
I have tested switching out the Esof relays, fuses and waiting on a part to try the esof solenoid. After this if not solve, should I try and change out the vacuum pump or is it maybe the gem module?
When I try to activate my ESOF switch inside the cabin I don’t get any actuation from the transfer case motor or vacuum pump kick on.
I have tested switching out the Esof relays, fuses and waiting on a part to try the esof solenoid. After this if not solve, should I try and change out the vacuum pump or is it maybe the gem module?
Logistics Pro
Joined: May 2017
Posts: 4,667
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From: Muskogee, Ok
When you turn the key to run with the engine off does the vacuum pump kick on? It should fire up for about 10 seconds when you initially turn the key for the first time before cranking the engine
Lead Driver
Joined: Oct 2005
Posts: 6,129
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From: Ponca City, OK
You might also check the large junction connectors. They are 3 largeish square plugs on the firewall down kinda low a little outside center to the drivers side. The contacts can corrode from moisture and road gunk and cause more than a few gremlins. Considering a large percentage of the chassis harness is in one or another of those plugs it's just a roll of the dice determining which thing goes bonkers.
Oh not sure if you're aware or not, but to shift to 4lo the brakes have to be pressed and the transmission in neutral.
Oh not sure if you're aware or not, but to shift to 4lo the brakes have to be pressed and the transmission in neutral.
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5th Gear
Joined: Nov 2024
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You might also check the large junction connectors. They are 3 largeish square plugs on the firewall down kinda low a little outside center to the drivers side. The contacts can corrode from moisture and road gunk and cause more than a few gremlins. Considering a large percentage of the chassis harness is in one or another of those plugs it's just a roll of the dice determining which thing goes bonkers.
Oh not sure if you're aware or not, but to shift to 4lo the brakes have to be pressed and the transmission in neutral.
Oh not sure if you're aware or not, but to shift to 4lo the brakes have to be pressed and the transmission in neutral.
Should I try some dialectical grease on them?
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Lead Driver
Joined: Oct 2005
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From: Ponca City, OK
You'd probably want to attempt to clean any corrosion before the dielectric grease. There's a line of products some of us have had luck with called Deoxit. I picked up some from Amazon, you might find some local but it does a decent job of cleaning electrical connections.
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5th Gear
Joined: Nov 2024
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You'd probably want to attempt to clean any corrosion before the dielectric grease. There's a line of products some of us have had luck with called Deoxit. I picked up some from Amazon, you might find some local but it does a decent job of cleaning electrical connections.
Lead Driver
Joined: Oct 2005
Posts: 6,129
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From: Ponca City, OK
Where the PCM connector goes through the firewall. If you look right of there(towards the engine) and down a little you should see 3 square plugs roughly 1 1/4" sq. From there they head under the cab. You probably have to access them from under the truck because of all the hydro booster and master cylinder crap, not to mention the IC tube and exhaust manifold.
Lead Driver
Joined: Aug 2022
Posts: 5,081
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From: Oologah, OK
Properly used, it is to pack the rear side of harness connections to Keep Water OUT.
This is what you paste on the terminals, and harness pins, very lightly, with a very small brush.... do NOT gob it on, or you will create a LOT of Problems.
Lead Driver
Joined: Jun 2004
Posts: 6,356
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From: Amarillo, TEXAS!
This is what you paste on the terminals, and harness pins, very lightly, with a very small brush.... do NOT gob it on, or you will create a LOT of Problems.
Carbon Conductive Grease
Carbon Conductive Grease
Lead Driver
Joined: Jul 2017
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From: WV
Originally Posted by Pikachu
This is a myth. Applying dielectric grease to the pins and sockets of a connector in good mechanical condition presents no problem.
What happens when you inadvertently bridge two circuits on a connector and fry a module?
What happens when you inadvertently bridge two circuits on a connector and fry a module?
https://www.ford-trucks.com/forums/1...l#post21160048
FTE Chapter Leader
Joined: May 2020
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From: Langley B.C. Canada
@F350towing may disagree after what he went through with dielectric grease on connectors.
https://www.ford-trucks.com/forums/1...l#post21160048
https://www.ford-trucks.com/forums/1...l#post21160048
NEVER put Dialectric Grease on connections, it is an Insulator.
Properly used, it is to pack the rear side of harness connections to Keep Water OUT.
This is what you paste on the terminals, and harness pins, very lightly, with a very small brush.... do NOT gob it on, or you will create a LOT of Problems.
Carbon Conductive Grease
Properly used, it is to pack the rear side of harness connections to Keep Water OUT.
This is what you paste on the terminals, and harness pins, very lightly, with a very small brush.... do NOT gob it on, or you will create a LOT of Problems.
Carbon Conductive Grease
Dielectric did in fact play havoc with my engine harness connections. So much that I had to remove all of it then wash each connection with Deoxit and Q-tips.
I did use a conductive grease ‘ VERY CAREFULLY’. I used a toothpick as the applicator to put a small amount only on the female pins.
Dielectric was then use appropriately just on the rubber seals.