Question about 2002 Ford Explorer
Problem started with bad altinator/dead battery. Charged battery, replaced altinator. charge system ok, battery good. When car was started 4x4 low push switch amber light on, dash icon 4x4 low on. push AWD or 4x4 high button no engagement, 4x4 low switch flashes, 4x4low dash icon remains on. Push 4x4 low again switch light remains on steady. Car will not move, apparently transfer case will not engage. Trans output shaft is turning because it will grind if I try to put it back in park. must shut down engine then place trans in park. No bangs, grinds vibrations ect when car was parked w/dead battery. 4WD system worked fine. Strange coinsidance or??????????
Posted by Anonymous on
The electronic module (located behind the glove compartment) controls the operation of the transfer case in response to inputs from the electric shift motor, 4x4 mode switch, CPP switch, BPP switch, DTR sensor, throttle position output from the PCM, front and rear OSS sensors, and the VSS. Do you know what DTC'S Are ? Diagnostic trouble codes !
P1804 4WD High Indicator Circuit Failure GEM GO to Pinpoint Test C . P1806 4WD High Indicator Short to Battery GEM GO to Pinpoint Test C . P1808 4WD Low Indicator Circuit Failure GEM GO to Pinpoint Test C . P1810 4WD Low Indicator Short Circuit to Battery GEM GO to Pinpoint Test C . P1812 4WD Mode Select Circuit Failure GEM GO to Symptom Chart. P1815 4WD Mode Select Short Circuit to Ground GEM GO to Symptom Chart. P1820 Transfer Case CW Shift Relay Coil Circuit Open or Short to Ground GEM GO to Pinpoint Test B . P1822 Transfer Case CW Shift Relay Coil Short to Battery GEM GO to Pinpoint Test B . P1824 4WD Electric Clutch Relay Circuit Failure GEM GO to Pinpoint Test A . P1826 4WD Electric Clutch Relay Short to Battery GEM GO to Pinpoint Test A . P1828 Transfer Case CCW Shift Relay Circuit Failure GEM GO to Pinpoint Test B . P1830 Transfer Case CCW Shift Relay Coil Short to Battery GEM GO to Pinpoint Test B . P1836 Transfer Case Front Shaft Speed Sensor Circuit Failure GEM GO to Symptom Chart. P1837 Transfer Case Rear Shaft Speed Sensor Circuit Failure GEM GO to Symptom Chart. P1838 Transfer Case Shift Motor Circuit Failure GEM GO to Pinpoint Test B . P1846 Transfer Case CONTACT PLATE "A" Circuit Failure GEM GO to Pinpoint Test B . P1850 Transfer Case CONTACT PLATE "B" Circuit Failure GEM GO to Pinpoint Test B .
P1854 Transfer Case CONTACT PLATE "C" Circuit Failure (GEM Only) GEM GO to Pinpoint Test B . P1858 Transfer Case CONTACT PLATE "D" Circuit Failure (GEM Only) GEM GO to Pinpoint Test B . P1866 Transfer Case Maintenance Required (GEM Only) (4-wheel drive operation can be restored by clearing the DTC and cycling the ignition.) GEM GO to Pinpoint Test B . P1867 Transfer Case Contact Plate General Circuit Failure (GEM Only) GEM GO to Pinpoint Test B . P1874 Automatic Hall Effect Sensor Power Circuit Failure GEM GO to Symptom Chart. P1875 Automatic Hall Effect Sensor Power Circuit Short to Battery (GEM Only) GEM GO to Symptom Chart. P1891 Transfer Case Contact Plate Ground Return Open Circuit GEM GO to Pinpoint Test B Your best bet , take it to a qualified repair shop
Posted on Apr 04, 2017
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.
Posted on Jul 10, 2010
Testimonial: "Thanks John. I now need to test to confirm this. Any suggestions."
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.
Posted on Mar 20, 2011
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.
Posted on Mar 26, 2011
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