Front axle solenoid override

[TraceF]

In older model GM trucks I put a toggle switch in-line on one of the two wires going to the front axle solenoid so I could have 2-wheel low range. It simply interrupts the electrical signal sent by the switch when 4 wheel drive is engaged so the front axle isn't pulling.

My 2008 has 4 wires going to the solenoid. Does anyone know how to accomplish this with the new wiring?

[More Power]

The new(er) systems monitor engagement of the front axle disconnect for proper activation. If you have an electric-shift transfer case, I'm not sure what would be the result if the front axle disconnect circuit was bypassed. It'll surely set a code, but I don't know if that would prevent the transfer case from engaging.

Jim

[TraceF]

The new(er) systems monitor engagement of the front axle disconnect for proper activation.

Jim

Thanks for thr reply- I have been trying to wrap my brain around this for a couple of days. I don't follow. The newer system monitors engagement of the front axle disconnect for proper activation of what? The TC?

Or are you saying for proper disengagement of the front axle?

[More Power]

There's a switch in the front axle that switches ON when the axle is engaged - and off when the axle is disengaged.

The Transfer Case Control Module (TCCM) and the vehicle ECM look at the axle switch position when the vehicle operator calls for 4WD. If that switch in the front axle doesn't switch on (indicating engagement), it'll cause an LED on the 4WD switch panel to flash, and this will be interpreted as a malfunction.

Back in 2004, I studied the 4WD system during the final stages of converting my 1989 Chevy K1500 to use the Duramax/Allison. I needed to get the earlier 4WD system to work correctly with the new electronics. In my case, I used a 2001 NVG-263 electric-shift transfer case.

Jim

[TraceF]

Is it possible to get manual locking hubs for these front axles?

How do I get to 2wd low range?

[TraceF]

There's a switch in the front axle that switches ON when the axle is engaged - and off when the axle is disengaged.

The Transfer Case Control Module (TCCM) and the vehicle ECM look at the axle switch position when the vehicle operator calls for 4WD. If that switch in the front axle doesn't switch on (indicating engagement), it'll cause an LED on the 4WD switch panel to flash, and this will be interpreted as a malfunction.

Back in 2004, I studied the 4WD system during the final stages of converting my 1989 Chevy K1500 to use the Duramax/Allison. I needed to get the earlier 4WD system to work correctly with the new electronics. In my case, I used a 2001 NVG-263 electric-shift transfer case.

Jim

Do you recall the 2-wire front axle solenoid? I think my 2000 model K2500 was the last truck where I put a toggle switch in-line by interrupting the black leg of the two wires.

Do you think the 2 extra wires in today's 4-wire connector are only for the system to monitor whether the front axle actually engages?

[More Power]

Do you recall the 2-wire front axle solenoid? I think my 2000 model K2500 was the last truck where I put a toggle switch in-line by interrupting the black leg of the two wires.

Do you think the 2 extra wires in today's 4-wire connector are only for the system to monitor whether the front axle actually engages?

The early 2-wire systems were most often seen as the thermo-actuator systems. An electrical heater heated a gas or liquid that expanded, thus extending the actuator. However, even these used a separate switch that made/broke contact - to indicate whether the axle was engaged - depending on the position of the locking gear inside the front diffferential.

The newer front axle actuator incorporated the "engaged" signal switch into the actuator itself, and didn't use a separate switch.

According to my 2001 service manual, the Front Axle Actuator electrical connector was configured like this:

A - blk/wht, (4WD Engaged Signal) 12 volts when 4WD engaged, open (0 volts) when disengaged.

B - lt blu, 4WD Relay Coil Supply, 12 volts when the Transfer Case Control Module (TCCM) asks for 4WD.

C - brn, 12 volts when ignition key in run/start.

D - not used

E - blk, Ground

Jim