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A. Penland, Ford Senior Master Technician, ASE
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Why wont four wheel drive on Ford Ranger engage?

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Why won't four wheel drive on Ford Ranger 1995 (6 cylinder standard) engage?

Hi,

Thanks for using Just Answer, the most common cause of the problem you are having is a defective transfer case shift motor. With an assistant helping, switch to 4wd tap on the transfer case shift motor with a hammer while the vehicle is running in nuetral and the parking brake applied. Hope this helps you out.

graphic

Component Tests

ISO Relay

Testing of an ISO relay can be accomplished through the use of three No. 10 (or larger) gauge jumper wires and a Rotunda 73 Digital Multimeter 105-R0051 or equivalent. Remove (unplug) the relay to be tested from the power distribution box, fuse junction panel or individual connector. Using the multimeter, check for continuity between terminal 85 and all other terminals. If resistance is 5 ohms or less between terminal 85 and any other terminal, replace the relay. If resistances are greater than 5 ohms, continue with test.

Using two jumper wires, connect relay terminals 86 and 30 directly to the positive battery (10655) terminal. Using the multimeter set in the volts position, check for voltage at terminal 87A. If battery voltage is not indicated, replace the relay. If battery voltage is indicated, connect a third jumper wire to terminal 85 and ground the jumper wire to a known good ground. Check for voltage at terminal 87. If battery voltage is not indicated, replace the relay.

Micro Relay

Testing of a micro relay can be accomplished through the use of three No. 10 (or larger) gauge jumper wires and a Rotunda 73 Digital Multimeter 105-R0051 or equivalent. Remove (unplug) the relay to be tested from the power distribution box, fuse junction panel, or individual connector. Using the multimeter, check for continuity between terminal 2 and all other terminals. If resistance is 5 ohms or less between terminal 2 and any other terminal, replace the relay. If resistances are greater than 5 ohms, continue with test.

Using two jumper wires, connect relay terminals 1 and 3 directly to the positive battery terminal. Using the multimeter set in the volts position, check for voltage at terminal 4. If battery voltage is not indicated, replace the relay. If battery voltage is indicated, connect a third jumper wire to terminal 2 and ground the jumper wire to a known good ground. Check for voltage at terminal 5. If battery voltage is not indicated, replace the relay.

4x4 Mode Switch - Ranger/Explorer

A variable resistance switch that signals the Generic Electronic Module to operate the "Control-Trac" (Explorer 4x4) or the "Select Drive" (Ranger 4x4), Four-wheel drive system in 2WD, 4WD High Ranger/4WD Auto Explorer and 4WD Low range. The switch is checked as follows:

Measure resistance between Circuits 359 (GY/R), 465 (W/LG) using Rotunda 73 Digital Multimeter 105-00051 (see diagram and table below for terminal location and resistance values).
Transfer Case Mode Switch


SWITCH RESISTANCE
Mode Switch PositionResistance (Ideal Ranges)
OPEN> 8.8K
Two-Wheel Drive8.7K to 2.0k Ohms
4WD High/Auto1.9K to 700 Ohms
4WD Low600 Ohms to 150 Ohms
Short to Ground< 150 Ohms

Brake Signal Input to the GEM

The brake signal input to the GEM is required to shift in and out of 4WD/Low. To verify the signal, gain access to Generic Electronic Module (GEM), Remove GEM Connector C3. Measure voltage at C3-13 harness side. With brake pedal depressed, voltage should be battery volt.

Transfer Case Shift Motor

The transfer case shift motor allows shifting between 2WD, 4WD high, 4WD low for Ranger and between 2WD, neutral and 4WD low for the Explorer.

The motor for the Ranger and Explorer have unique connectors. The position of the motor may be verified using the tables below along with the associated diagrams.

Explorer - Continuity is measured between shift motor Connector Pin 10 and the pins listed below.

Connector PinSensor Position Feeds to the GEM
Mech StopL2H Stop2H2H EaN EaN4L Ea4LH2L Stop
5111110001
1000111111
9011111100
13001100111

a I - Ground
O - Open
E - Edge Transitional State (Non-Driveable)

Ranger - Continuity is measured between shift motor Connector Pin 6 and the pins listed below.

Connector PinSensor Position Feeds to the GEM
Mech StopL2H Stop2H2H EaN EaN4L Ea4LH2L Stop
5111110001
1000111111
2011111100
3001100111

a I - Ground
O - Open
E - Edge Transitional State (Non-Driveable)

Customer: replied 6 years ago.

Hi,
I put engine on in neutral with p brake applied, did hit motor with hammer. No response. However motor would activate when connected directly to 12 source., so doesn't that mean it's working??
RE: Component tests: I'm not getting it. Some of the images you sent didn't come thru Maybe they'd help me understand some of this. Here goes:
Where are the ISO relays located? Are you talking about the square relays in the D box under hood? Could I just get replace the ones labeled in Owner's Manual as having to do with four wheel system?
Are the Micro relays something else? Where are they located? Are they the fuses in the fuse panel at side of dash drivers side?
Where is Terminal 85 and other terminals located?
Where is the GEM located? Like I say, I've got half the interior apart.
Measure voltage at C3-13 harness side. Is this labeled on the unit?
Ranger - Continuity is measured between shift motor Connector Pin 6 and the pins listed below.
So I could check to see if motor is working properly by checking continuity between the various pins. That I get. But the image didn't come thru. The image would show me the pin configuration I'm thinking?

Hi,

Here you go.

Generic Electronic Control Module (GEM), Central Timer Module (CTM)

Removal and Installation

  1. Disconnect battery ground cable.
  2. Remove radio.
  3. Remove radio bezel.
  4. Remove retaining screw.
  5. Slide GEM/CTM toward front of vehicle, off retaining tabs.
  6. Disconnect electrical connectors

graphic

NOTE: When the battery (10655) has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) (12A650) relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 miles) or more to relearn the strategy.

For installation, follow removal procedures in reverse order. Tighten retaining screw to 2.3-3.3 Nm (20.4-29.2 lb-in).

NOTE: The automatic ride control switch must be turned to the OFF position when the vehicle is hoisted, jacked, towed, jump-started or raised off the ground to avoid unnecessary operation of the system and/or possible damage to its components.

Customer: replied 6 years ago.

I'm a DIY guy who can do some electrical checking when I have schematics and a relatively non-technical info AND ALL the images accompanying the technical directions. But what I mostly need is answers to my specific questions. That will help me with the decision tree on what is most likely to be problem, then next most likely etc. You know, like your best guesses based on your experience. Or if you think I'm over my head with the diagnosing of this particular then tell me that.

I've ordered a dash selector switch from Ford based on fact motor is operable under hot wire and switch is cheapest part of component link (excluding relays).

Hello,

The 4x4 system in your Ranger is controlled by the GEM module. It is located behind the radio to the left side of the radio opening. The best way to find out what is wrong with your 4x4 is to get a hold of a scan tool that can communicate with the GEM module. Below is a symptom chart and a list if the symptoms and the codes (DTCs) that you will get from the GEM module.

Section 07-07A: Transfer Case, 4x4 System, Service1995 All Aerostar, Ranger and Explorer Vehicles Workshop Manual

DIAGNOSIS AND TESTING - RANGER, EXPLORER

Symptom Chart - Electronic Shift Transfer Case Diagnosis, Ranger, Explorer

NOTE: Use Rotunda 73 Digital Multimeter 105-00051 with Rotunda Terminal Adapter Kit 105-00025 or equivalent to perform electrical pinpoint test.

ELECTRONIC SHIFT TRANSFER CASE DIAGNOSIS, RANGER, EXPLORER
ConditionPossible SourceAction
  • Cannot Change the 4WD Mode
  • DTC P1812, P1815 self test and continuous.
  • DTC P1803 self test, P1802 continuous.
  • SHORT to battery between the neutral safety switch and GEM Circuit 463 (R/W) or OPEN circuit.
  • DTC B1483 continuous. DTC B1485 self test and continuous.
  • GO to Pinpoint Test Step A6 .
  • Cannot Change 4WD Gears
  • DTC P1820 self test and continuous.
  • GO to Pinpoint Test Step B1 .
  • DTC P1822 self test and continuous.
  • GO to Pinpoint Test Step B5 .
  • DTC P1824 self test and continuous.
  • GO to Pinpoint Test Step B9 .
  • DTC P1826 self test and continuous.
  • GO to Pinpoint Test Step B10 .
  • DTC P1820, P1828 self test and continuous.
  • GO to Pinpoint Test Step B14 .
  • DTC 1828 self test and continuous
  • GO to Pinpoint Test Step B15 .
  • DTC P1830 self test and continuous.
  • GO to Pinpoint Test Step B21 .
  • DTC P1838 continuous.
  • GO to Pinpoint Test Step B22 .
  • DTC P1846, P1867 self test.
  • GO to Pinpoint Test Step B33 .
  • DTC P1850 self test; P1850, P1867 continuous.
  • GO to Pinpoint Test Step B35 .
  • DTC P1854, P1867 self test.
  • GO to Pinpoint Test Step B37 .
  • DTC P1858, P1867 self test.
  • GO to Pinpoint Test Step B39 .
  • DTC P1862 self test and continuous.
  • GO to Pinpoint Test Step B41 .
  • DTC P1864 self test.
  • GO to Pinpoint Test Step B43 .
  • DTC P1848 self test and P1866 continuous.
  • GO to Pinpoint Test Step B45 .
  • DTC P1852 self test and P1866 continuous.
  • GO to Pinpoint Test Step B46 .
  • DTC P1856 self test and P1866 continuous.
  • GO to Pinpoint Test Step B47 .
  • DTC P1860 self test and P1866 continuous.
  • GO to Pinpoint Test Step B48 .
  • Cannot Engage the 4WD
  • DTC P1833 self test and continuous.
  • GO to Pinpoint Test Step C1 .
  • DTC P1834 self test and continuous.
  • GO to Pinpoint Test Step C3 .
  • DTC P1842 self test and continuous.
  • GO to Pinpoint Test Step C5 .
  • DTC P1845 self test and continuous.
  • GO to Pinpoint Test Step C7 .
  • 4WD Is Always Active
  • DTC P1835 self test and continuous.
  • GO to Pinpoint Test Step D1 .
  • 4WD HIGH Indicator Lamp Never Illuminates
  • DTC P1804 self test and continuous.
  • GO to Pinpoint Test Step E1 .
  • DTC P1806 self test and continuous.
  • GO to Pinpoint Test Step E5 .
  • 4WD HIGH Indicator Lamp Is Always On
  • DTC P1804 self test and continuous.
  • SERVICE Circuit 783 (GY) for short open or to ground between GEM module C3-14 and indicator lamp.
  • 4WD LOW Indicator Lamp Never Illuminates
  • DTC P1808 self test and continuous.
  • GO to Pinpoint Test Step F1 .
  • DTC P1810 self test and continuous.
  • GO to Pinpoint Test Step F5 .
  • 4WD LOW Indicator Lamp Is Always On
  • DTC P1808 self test and continuous.
  • SERVICE Circuit 784 (LB/BK) for short or open to ground between GEM module C3-10 and indicator lamp.
  • 4WD System Drains Battery
  • Defective wiring.
  • SHORT to battery Circuit 705 (LG/O) to the H2L relay.
  • 4WD Mode Switch Does Not Illuminate with Headlamp Switch ON
  • Open circuit, short to ground, defective 4x4 switch.
  • Automatic 4WD Erratic Operation
  • DTC P1836, P1837 or P1874 self test.
  • Transfer Case (7A195) Makes Noise
  • Incorrect tire inflation pressures or incorrect size tires and wheels.
  • MAKE SURE that all tires and wheels are the same size, and that inflation pressures are correct.
  • Excessive tire tread wear.
  • CHECK tire tread wear to see if there is more than .06 inch difference in tread wear between front and rear. INTERCHANGE one front and one rear wheel. REINFLATE tires to specifications.
  • Internal components.
  • OPERATE vehicle in all transmission gears with transfer case in 2HI, or High range.
  • If there is noise in transmission (7003) in neutral gear, or in some gears and not in others, REMOVE and REPAIR transmission.
  • If there is noise in all gears, OPERATE vehicle in all transfer case ranges. If noisy in all ranges or High range only, DISASSEMBLE transfer case. CHECK input gear, intermediate and front output shaft gear for damage. REPLACE as required. If noisy in Low range only, INSPECT intermediate gear and sliding gears for damage. REPLACE as required.
  • 4-Wheel Drive Transfer Case Jumps Out of Gear
  • Incomplete shift linkage travel.
  • ADJUST linkage to provide complete gear engagement. ADJUST shift gearshift lever boot (7277).
  • Loose mounting bolts.
  • TIGHTEN mounting bolts.
  • Front and rear driveshaft slip yokes (4841) dry or loose.
  • LUBRICATE and REPAIR slip yokes as required. TIGHTEN flange yoke attaching nut to specifications.
  • Internal components.
  • DISASSEMBLE transfer case. INSPECT sliding clutch hub and gear clutch teeth for damage. REPLACE as required.
  • Locking Hubs Will Not Release
  • Driveline/vehicle torsional lockup.
  • STOP vehicle. DRIVE vehicle in reverse for 3 meters (10 feet).
  • Extremely cold ambient temperatures.
  • DRIVE vehicle 16 km (10 miles) to warm axle, then try to DISENGAGE hub locks.
  • Driveline/Torsional Windup. Vehicle Hop, Wheel/Tire Bounce, Vehicle Skip
  • Incorrect tire inflation pressures or incorrect size tires and wheels.
  • MAKE SURE that all tires and wheels are the same size, and that inflation pressures are correct.
  • Excessive tire tread wear.
  • Driving vehicle on hard surface/dry surface roads or areas. Driving vehicle in tight turns.
  • REFER to vehicle owner's guide for correct usage of vehicle. ADVISE owner.
  • Delayed Shifts to 2WD
  • Driveline/torsional windup.
  • SHIFT transmission into neutral. JACK the vehicle or lift on hoist with wheels free to rotate. Windup will be released and transfer case will complete its shift.
  • Extremely cold ambient temperatures.
  • DRIVE vehicle 16 km (10 miles) to warm axle, then try to DISENGAGE hub locks.
Customer: replied 6 years ago.

I've got an OBD hand held scanner tool which won't communicate with GEM. Am I basically looking at having a garage diagnose the problem?

They can atleast get you the codes. They might charge you for them, that is if you want to repair the problem yourself. But just throwing parts at it cost way too much in cash and aggravation.

A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 5995
Experience: ASE Master Certified, ASE Advanced Gasoline Engine Performance
A. Penland and 7 other Ford Specialists are ready to help you
Customer: replied 6 years ago.

Agreed. I'll take a shot with switch then if no go will have a diagnostic done and I'll install parts. Just have to hotwire the truck OUT of 4 wheel low and get it to garage! Thanks for perspective.

No problem, sorry I couldn't give you a definite repair to your problem. But electronics and modules are tricky items to work with.

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