I have a 98 F150, with shift on the fly 4wd. When I start the truck it shifts into 4wd automatically, moving the **** does nothing. If I drive it, the 4x4 light on the dash will light up of off and click rapidly. If I happen to stay in neutral, it will then go into low on it's own. I've checked the fuses and tried to disable it this way. Anyone have any ideas on how I can at least keep it out if 4wd for now? Thanks

John

 

Not sure if this will help, but sometime I have to drive in reverse for about 10' or so to get it disengaged.


Rick

 

Thanks Rick. This has to do with the 4x4 staying engaged all the time now, the light on the dash remains on even though the **** is not in 4wd.

John

 

Do you have mechanical or electronic shift on the fly? If it's mechanical it is probably the 4wd indicator switch located on the front of the transfer case. The little ball bearing in the switch tends to stick.

 

It's electronic. Thanks

 

Well here is the diagnostic routine from my 97 factory cd. A 98 should be the same or very similar. I would start with the 4wd mode switch. Here are the resistance values:

2WD = 4100-3700ohms
4HI = 1050-1150ohms
4LOW = 380-340ohms

Good Luck!



PINPOINT TEST A: VEHICLE DOES NOT SWITCH BETWEEN 2WD AND 4WD MODES PROPERLY
² A1: CHECK THE VOLTAGE OUTPUT FROM FUSE 15 (5A)
² A2: CHECK FUSES 15 (5A) and 22 (50A)
² A3: CHECK CIRCUIT 1052 (T/BK) FOR VOLTAGE
² A4: CHECK IGNITION STATES
² A5: RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCs)
² A6: CHECK THE HIGH LAMP INDICATOR
² A7: CHECK THE LOW LAMP INDICATOR
² A8: CHECK THE 4WD MODE SWITCH PID — 2H
² A9: CHECK THE 4WD MODE SWITCH PID — 4H
² A10: CHECK THE 4WD MODE SWITCH PID — 4L
² A11: CHECK THE 4WD MODE SWITCH — 2H
² A12: CHECK THE 4WD MODE SWITCH — 4H
² A13: CHECK THE 4WD MODE SWITCH — 4L
² A14: CHECK CIRCUIT 780 (DB) FOR OPEN
² A15: CHECK CIRCUIT 780 (DB) FOR SHORT TO GROUND
² A16: CHECK CIRCUIT 780 (DB) FOR SHORT TO POWER
² A17: CHECK CIRCUIT 682 (DB) FOR OPEN
² A18: CHECK CIRCUIT 682 (DB) FOR SHORT TO GROUND
² A19: CHECK CIRCUIT 682 (DB) FOR SHORT TO POWER
² A20: CHECK THE FRONT AXLE ENGAGEMENT
² A21: CHECK THE FRONT DRIVESHAFT ENGAGEMENT
² A22: CHECK THE FRONT DRIVESHAFT DISENGAGEMENT
² A23: CHECK THE FRONT AXLE DISENGAGEMENT
² A24: CHECK THE TRANSFER CASE SHIFT RELAYS COIL CIRCUITS — ACTIVATED
² A25: CHECK THE TRANSFER CASE SHIFT RELAYS COIL CIRCUITS — DE-ACTIVATED
² A26: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT RELAYS COILS
² A27: CHECK CIRCUIT 781 (O/LB) FOR OPEN
² A28: CHECK CIRCUIT 782 (BR/W) FOR OPEN
² A29: CHECK CIRCUITS 781 (O/LB) AND 782 (BR/W) FOR SHORT(S) TO GROUND
² A30: CHECK CIRCUIT 782 (BR/W) FOR SHORT TO POWER
² A31: CHECK CIRCUIT 781 (O/LB) FOR SHORT TO POWER
² A32: CHECK THE TRANSFER CASE SHIFT RELAYS COILS
² A33: CHECK THE VOLTAGE TO THE ELECTRIC SHIFT MOTOR — MOTOR ON
² A34: CHECK THE VOLTAGE TO THE TRANSFER CASE SHIFT RELAYS SWITCH
² A35: CHECK THE VOLTAGE TO THE ELECTRIC SHIFT MOTOR — MOTOR OFF
² A36: CHECK CIRCUITS 777 (Y) AND 778 (O) FOR SHORT(S) TO POWER
² A37: CHECK CIRCUITS 777 (Y) AND 778 (O)
² A38: CHECK CIRCUIT 777 (Y) FOR OPEN
² A39: CHECK CIRCUIT 778 (O) FOR OPEN
² A40: CHECK THE GROUND TO THE TRANSFER CASE SHIFT RELAYS
² A41: CHECK THE CONTACT PLATE SWITCHES
² A42: CHECK THE CIRCUIT 771 (P/Y) TO THE CONTACT PLATE SWITCH A
² A43: CHECK CIRCUIT 771 (P/Y) FOR SHORT TO GROUND
² A44: CHECK CIRCUIT 771 (P/Y) FOR OPEN
² A45: CHECK CIRCUIT 771 (P/Y) FOR SHORT TO POWER
² A46: CHECK CIRCUIT 762 (Y/W) FOR SHORT TO POWER
² A47: CHECK CIRCUIT 762 (Y/W) FOR OPEN
² A48: CHECK THE CIRCUIT 770 (W) TO THE CONTACT PLATE SWITCH B
² A49: CHECK CIRCUIT 770 (W) FOR SHORT TO GROUND
² A50: CHECK CIRCUIT 770 (W) FOR OPEN
² A51: CHECK CIRCUIT 770 (W) FOR SHORT TO POWER
² A52: CHECK THE CIRCUIT 764 (BR/W) TO THE CONTACT PLATE SWITCH C
² A53: CHECK CIRCUIT 764 (BR/W) FOR SHORT TO GROUND
² A54: CHECK CIRCUIT 764 (BR/W) FOR OPEN
² ***: CHECK CIRCUIT 764 (BR/W) FOR SHORT TO POWER
² A56: CHECK THE CIRCUIT 763 (O/W) TO THE CONTACT PLATE SWITCH D
² A57: CHECK CIRCUIT 763 (O/W) FOR SHORT TO GROUND
² A58: CHECK CIRCUIT 763 (O/W) FOR OPEN
² A59: CHECK CIRCUIT 763 (O/W) FOR SHORT TO POWER

 

Have you had it in 4 wheel drive lately? If so your electric motor has probably gone out. It is easy to replace. You can always take it off and leave it plugged up then turn your 4x4 switch and see if the motor turns. It only makes about a 1/2 turn.

Good luck!

 

i have a 97 f150 4x4 and im having the same exact problem and i went and bought a new transfer case motor, 200+, and im still having the same problem. seems that when i engage the four wheel drive sometimes it goes in but it will not come back out. also sometimes the four wheel drive lamp will not light up when i turn the switch until i drive about 5 feet. but its exactly the same symptoms as you are having. i have an appointment with the dealer on friday but really dont want to take it in. i sometimes think i know more than they do. if anyone can help us because its not the t case motor i bought one and its doing the exact same thing after the new one. i see all the things to check but im not really good with pinpointing electrical problems. any help would be appreciated or a fix thanks, john

 

Sounds like you may have a shifting fork problem in your transfer case. as far as engaging the front axle,thats done by
by a vacuum motor up on the axle. I think pulling the vacuum line
off will disengage the axle.
( my 4x4 wouldn't engage when the vacuum line got ripped off fourbying.)

 

Dont' forget to check your fluid level!