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My 4x4 quit working. It will not shift into 4H or 4L
The following is what I am seeing-
Voltages at the on the fly selector switch look good- 3 voltage steps from about 5.5v down to .9v at pin3 which goes to the GEM C241 pin 8
Transfer Shift relay module-
pins 3&5 14v
pin 7 no voltage
pins 8&9 both have 14v
It appears the GEM isn't providing the low to make the relays engage the transfer case motor.
I'm not sure i have the correct drawing for my year. I am using 034-001 and 034-002 that I found on an internet search.
My questions are-
1) When the 4wd mode switch is to 4H is there some interlock that has to be met before it sends the low out to pin 8 (of the transfer case shift relay module) to engage the shift motor?
2) does the 2003 f150 have a transfer case electric clutch relay shown on drawing 034-002?
Any assistance you can provide would be greatly appreciated.
The electric shift schematic shown is only half the system.
You need to check overall operation first instead of getting into the weeds and getting confused.
A. Dash switch only requests the GEM to operate the case motor and the Sync clutch plus rotates a rod to connect the gear train to the case.
B. The case motor 'Circuit board" internal to the case motor connects through the Gem to the firewall solenoid as control and progress signals.
C. This transfers engine vacuum to the front axle Actuator resulting is a splined collor connecting two halves of the passenger side CV axle.
Check what part does not perform or where the system stops first before diving into the weeds on troubleshooting.
This is why your now here.
Good luck.
The electric shift schematic shown is only half the system.
You need to check overall operation first instead of getting into the weeds and getting confused.
A. Dash switch only requests the GEM to operate the case motor and the Sync clutch plus rotates a rod to connect the gear train to the case.
B. The case motor 'Circuit board" internal to the case motor connects through the Gem to the firewall solenoid as control and progress signals.
C. This transfers engine vacuum to the front axle Actuator resulting is a splined collor connecting two halves of the passenger side CV axle.
Check what part does not perform or where the system stops first before diving into the weeds on troubleshooting.
This is why your now here.
Good luck.
the transfer case is not shifting- A- the signal at the case motor is not there, hence my question- is there any interlock or is the switch the only thing that is needed to make the transfer case shift.
doesn't the transfer case need to change before the front axle comes into play?????
There is no interlock involved in 4H operation.
Only interlock is going to 4L were the vehicle has to be stopped, in Neutral and foot applied to brake.
The GEM operates a relay that passes fused power to the case motor.
If that is not happening, that is the stopping point.
Find out why power is not being applied to the relay and getting to the case motor.
Is it the GEM, a Fuse, the relay, the harness or the case motor?
Nothing else will work until the case motor runs to first position.
It is a progression system that reverses in 2wd switch position. The relay reverses power to the case motor to run it reversed as shown on the schematic. None of it is digital, all analogue.
