4x4 low light on car will not move

SOURCE: A4LD 4X4. trans. wont engage into gear

It grinds just sitting still? Will it do it with the transfer case in neutral or 4x4?

Johnny Brown

• 5763 Answers
• Posted on Jul 10, 2010

SOURCE: 4x4 lights flash, will not engage into 4wd

This is called the selector motor and you may be correct this is a common problem with these trucks the selector motor goes bad and will not engage the correct gear setting you select.

Testimonial: "Thanks John. I now need to test to confirm this. Any suggestions."

SOURCE: 1996 ford explorer 4x4 only

sounds like your transmission is starting to go out.

SOURCE: My 98 f150 was in 4WD Hi this morning when I

If the switch was in the 2WD position and the transfer case was locked in a 4WD range, my 2 SWAGs would be bad switch or the connector to the shift motor is damaged / corroded or the fuse to the transfer case shift relay module is blown ( fuse # 17 ) / problem with the transfer case shift relay module.

This is without knowing if the truck was used in 4WD the night prior, and shifted out just before turning off. If this is the case, the shift motor might be stuck, and a few hits with a dead blow hammer to the transfer case might jar it free again ( do not use a metal hammer, it could damage the transfer case ).

The vacuum shift solenoids on the firewall are controlled by the GEM ( Generic Electronic Module ) which is grounding either the 2WD or 4WD solenoid, depending on the shift plate contacts in the transfer case. ( when in 4 or 4H, the contact switch plate signals the GEM, which in turn grounds the correct solenoid ).

Pulling the switch will not cause the transfer case to go back to a default position, the switch has a resistance level for each mode, and needs that value to operate the shift motor.

The resistance values for the switch between the 2 dark blue wires:
2WD - 4100 to 3700 ohms
4H - 1050 to 1150 ohms
4L - 380 to 340 ohms
- find the wire locations on the switch, mark them and remove the connector to test the resistance.

Just my opinion on the order :

1. Check the fuses for the shift motor
2. Try the old school shift method, back up ~ 50' put into park or neutral, and shift from 4WD to 2WD.
2.1. This is to see if the transfer case shift motor is bound up, and reversing might release it
3. Try hammering the transfer case with a dead blow hammer while someone shifts from 2WD to 4WD. You only need the key in the run position, if it happens quick enough after running the engine, the vacuum reservoir will still have enough vac to operate the solenoids. Don't chance running yourself over.
3.1. If this frees up the shift motor and the vacuum has bled off, you can try starting the truck and shifting into 4H then back to 2WD to get the front axle to disconnect or manually vacuum operate the front disconnect motor by applying vacuum to the pink vacuum line on the shift motor on the front axle.

SOURCE: I own a 1999 Expedition

This is very strange because of How the low range is engaged. I drive a 1999 F150 4x4 which has the same dash and controls for the 4x4 as your Expedition. I do know that the fan control switch is unfortunately the same shape and very close to the 4x4 switch. It is easy to grab the wrong knob and turn the wrong thing than was intended.

My initial impression is if it is possible, your girl could have reached over to move the fan switch and actual grabbed the 4x4 switch instead. Or you were warming up the Expedition and meant to turn up the fan and instead turned the 4x4 switch to Low. Or a backpack she was moving with schoolbooks could have hit the switch. What puzzles me is that to go into Low range, you need a foot on the Brake and simultaneously need the gearshift in Neutral and the 4x4 selector in Low. That is 3 things to make the low range happen.

Even if your foot was on the Brake and the sensors caught the gearshift going through Neutral on its travel to Park, the 4x4 Selector would have to be in Low. There is one problem you can have with the 4x4 Selector.***The Selector has 3 Resistors and a LED bulb.***

You stated the Selector switch was good. This would mean there were 3 different Voltages under the vehicle. Sometimes when the LED bulb burns out, it shifts the Voltage out of range for the Servo, and although the Selector says one thing, the Voltage at the Servo has the wrong value for that function. Since the dash light and the Servo agree on Low, it would seem the Selector is out of sync with the other 2 parts.

I hope my solution is very helpful in solving your problem.