40series

My truck is stuck in 4 hi. I started by checking my grounds.The actuator plug cable doesn't have ground to it

RB04Av

Seems like at least one wire should.

Might wanna consult your FSM and see which one, and track it back, figure out why it's loose, fix it, and see what happens.

strutaeng

...why don't you simply add a ground (from the frame) to the connector, just to get it working? That's pretty easy.

Then figure out why the ground is missing.

My 04 Suburban had the entire bundle of wire severed. Like if was somehow stuck on the front driveshaft somehow. I respliced the harness, and my "service 4wd" message was still there and it was still stuck in 2wd. It would up being the little reluctor wheel inside the encoder motor. I think it's called range something it's $20.

40series

I saw a guy splice the ground black wire before it went into the next connector around the wheel well and it worked for him. I think I'm going to check the switch tomorrow. Because I'm only getting a 4 low selection on the switch

arthursc2

iTrader: (5)

You may also need to pull your switch apart and reflow the solder contacts, that is pretty common

RB04Av

So, I happened to have that schematic up, and looked at it, and it turns out, none at all of the wires going to the whole assembly are grounded. I was wrong about that.

Inside it, it has the shift motor (has 2 wires, they are driven with 12V & gnd by the control module, hooked up one way to drive it in one direction and the other to go the other way), the brake solenoid (also 2 wires, one is constant 12V and the other is driven by the module), and the encoder (6 wires: 1 is 8V constant "reference", 1 is a common to 4 switches in there that get connected to it depending on which position it's in, and 4 are the 4 switch outputs). No dedicated ground.

If the unit won't shift, but you don't ever get the "Service 4WD" message and it doesn't light the red Neutral light when you try to shift it, it probably needs the motor.

40series

The black wire that comes out of the actuator solenoid is grounded ran under the driver's seat frame

RB04Av

There is no "actuator solenoid". There's a MOTOR, that turns in one direction, say, to go from 2 HI to 4 LO (not sure this is the exact sequence, just, that's the order of the buttons on the dash) and the other direction to go from 4 LO toward 2 HI. There's a red wire and a black wire at the MOTOR, both of which go to the ECM. It may well be that when you measure the black wire AT THIS MOMENT, that it ends up at ... a ground. However, the way the circuit works, as posted above, is that the ECM sends 12V down one of those wires (let's say, the red one) and ground down the other (the black one in this case), to make the motor go one way (say, 2 HI to 4 LO); and REVERSES those to turn the motor to spin the shaft the OTHER way (let's say, 4 LO toward 2 HI), at which time the RED wire would appear to be grounded. The wires out of the encoder motor are labelled on the factory schematic as "Motor (CCW) Red" and "Motor (CW) Blk". Not that the factory knows how they built the harness; maybe you "know" more than they do. That DOES happen of course, if not very often.

As said, there IS NO wire at the encoder motor, that is full-time grounded. What you MEASURE is not the same as WHAT IS at all times since the ECM controls which wire is connected to what at any given moment, even if AT THIS MOMENT, they happen to have continuity that particular way.

If you're struggling to understand this, go buy the FSM and see for yourself. Maybe $15 - 20 on fleabay. If you don't have that, then quit arguing, and listen to the info you're being given FREELY by someone who ALREADY spent that money FOR YOU. Otherwise, my truck works, and your doesn't. Sux to be u. Enjoy your arguing, just, go do it with somebody else, because I can no longer be bothered.

40series

I found a bad ground off the actuator and grounded it then turned key but not start I could hear the actuator engage then service 4 wheel light came back on and truck stayed in 4 wheel hi

RB04Av

Since there's no "ground off the actuator" at all, as described elsewhere after a detailed study of the schematic, what did you ACTUALLY ground?