1998 Navigator NO low range

[rockinrolla]

Hello everyone I'm a newbie. I have a 1998 navigator i just got recently and cannot get 4x4 low to work it has the selector dial options for 2wd,a4wd,4hi,4low. The A4wd and 4 high work fine can hear relays clicking and motor engaging 4 hi. I've tried stop depress brake and put in neutral and switching to 4 low nothing no clicking or motor sound I've checked all the wiring to the shift motor and check for corrosion nothing.The actuator is working all the fuses are good. I pulled the shift motor and manually put it in 4low with pliers and it works so it's not the transfer case.I watched the motor off the transfer case while someone else put it in low range and the motor did not spin any thoughts? thank you. Also the low range dash light has never come on even when i first start the truck

 

[bedrck46]

The Vehicle Does Not Shift Between 4WD HIGH and 4WD LOW Modes Properly

A4WD mode switch/circuit.
VSS.
BPP switch.
Transfer case shift relays.
Transfer case mechanism.
Transmission range sensor.
GEM.
Digital transmission range (DTR) sensor

 

[bedrck46]

Measure the resistance between mode switch terminals 2 and 3 while rotating the mode switch through all positions; refer to the following chart:
Switch Position Resistance Range
2H 3705-4095 ohms
A4WD 1425-1575 ohms
4H 646-714 ohms
4L 228-252 ohms


Also check the brake switch it is possible that the circuit for the 4L could be the problem. the brake switch has two circuits that it controls

also check the shift relays

prints attached

 

[rockinrolla]

Will check today thanks

 

[bedrck46]

I was wrong about the brake switch the 98 switch only had one circuit for the switch should just be a light green and light green/red wire for the switch

 

[rockinrolla]

where do i connect the ohm meter to the selector wires? dark blue?

 

[bedrck46]

yes to the two dark blue wires

 

[rockinrolla]

I'm sorry I've been busy and I went out of town. The ohm readings were different every time I touched the wires, and it would only show the ohms for a second on each mode. Also I have to put it in neutral to engage 4 hi it would not engage in drive. Thanks for the help!

 

[bedrck46]

you need to disconnect the connector from the switch and read across pins 2 and 3 and read the ohms in each position

 

[rockinrolla]

I did that and it gave different readings each time on each section only showed for a sec.

 

[bedrck46]

if you were reading directly at the switch you should get a steady reading at each position if your not then I would suspect that the switch is bad or your meter isn't reading correctly

check rock auto or e-bay for a new switch

What brand and model meter are you using
Have you tested it on a good known source.
Take and touch the two leads of the meter and see what reading you get.

 

[rockinrolla]

it's a brand new fluke meter so it's not that is there away to bypass the switch?

 

[rockinrolla]

also used a scanner didn't have any codes so I pulled up the memory and found a p1812 4wd mode select circuit fail could that be a switch? I think its strange that i have to push the brake for 4 hi and A4WD

 

[bedrck46]

I know you have already done this Just copied the following for your information

Measure the resistance between mode switch terminals 2 and 3 while rotating the mode switch through all positions; refer to the following chart:
Switch Position Resistance Range
2H 3705-4095 ohms
A4WD 1425-1575 ohms
4H 646-714 ohms
4L 228-252 ohms

If you are not getting a steady OHM reading when you test the switch then the switch is most likely bad

Only way to bypass the switch would to get 4 resistors in the required range and install them one at a time to see if the transfer case goes through all the positions

Or try a junk yard or you-pull it yard and take your meter along and find a good switch

 

[bedrck46]

What has me concerned is that your not getting steady OHM readings check all contact points to make sure you are on a clean contact surface or make up jumpers using spade connectors to put on pins 2 and 3 and retest switch also use some contact cleaner and clean all contact surfaces

 

[bedrck46]

When you are driving Can you switch into A4WD and 4hi just by turning the switch

 

[bedrck46]

I would assume that when you normally start the expy that you are in park.

Are you able to start the expy if the gear shift is in Neutral?

 

[stamp11127]

If your test leads came with alligator clips try those on the connectors of the switch. Sounds like you're not getting good contact when trying to read the values.

 

[rockinrolla]

When you are driving Can you switch into A4WD and 4hi just by turning the switch

Only in neutral with the brake applied

 

[rockinrolla]

I would assume that when you normally start the expy that you are in park.

Are you able to start the expy if the gear shift is in Neutral?

Yes i can start in neutral