'98 Ford Ranger Issues with 4x4 TCSM?

[DavidG]

Hi everyone. I have a 1998 Ford Ranger 4.0 4x4 and am having an issue with the 4x4 system. When the switch on the dash is set to 2WD, the 4hi and 4lo lights flash 6 times every two minutes and I can't engage either 4HI or 4LO.

In doing some research, a number of people said that it might be the transfer case shift motor and I looked in to buying a new one and looked at what I have compared to pictures of new motors. What I'm seeing is that, in addition to the bundle of wires in a plug of the shift motor, I also have a brown wire that come out the plug and goes into the transfer case.

The problem is that the shift motors I see online only have the wire bundle that goes in to the plug and don't have a single brown wire that isn't part of the bundle like my shift motor.

Does anyone have a single wire coming from the shift motor plug that goes into the transfer case or, if not, know what the wire is for?

I've had quotes anywhere from $150 - $200 just to diagnose the problem and a new shift motor is about $90 and that's why I thought I would give it a go.

Thanks and I appreciate any advice you have.

David

 

[RonD]

Yes, the flashing 4WD lights usually indicate shift motor is not responding to "commands" from the controller(GEM module in 1998)
Might be the Dual Relay box behind GEM but they rarely broke


First check the fuse in engine bay fuse box, Fuse 3 20amp, its for the shift motor

The brown wire is for the electric clutch inside the transfer case
If you have converted to manual hubs then you don't needed it

If you still have the PVH automatic hubs then you do need it if you what to "shift on the fly" from 2WD to 4High

The connector for shift motor only needs 7 wires, the connector has room for 8 pins/wires
On earlier years the brown wire was separate, not in the connector, but on some years it was added to connector
All shift motors only come with 7 wires on the connector

So you have two options
1. cut the brown wire from both sides of current connectors and splice the ends together
2. have manual hubs and just cut the brown wire off the current shift motor's connector and hook up the new shift motors connector, tape brown wire to those wires, so its not loose

Well three options, lol
Take the old shift motors connector apart and pull out the brown wire with pin attached
Then you can re-pin the new shift motor's connector with brown wire as 8th wire


Electric clutch
With automatic front hubs the front driveshaft and chain drive in transfer case are not spinning at rear drive shaft RPMs when hubs are unlocked, front drive shaft is at 0 RPMs
When you want to shift from 2WD to 4High you need to match rear drive shaft RPMs and front drive shaft RPMs
You can either stop , both at 0 RPMs, and shift, or use a clutch to spin up the front drive shaft/chain to match rear drive shaft RPMs while moving and engage automatic hubs
"Shift on the Fly"

If you have manual hubs and they are LOCKED or in the case of 2001 and up Rangers with Live Axle(always locked) then the front driveshaft and rear drive shaft are ALWAYS spinning at the same RPM, no clutch needed, and same "shift on the fly" available


Word of advise, to anyone with electric shift 4WD
Most shift motors die from DISUSE, not overuse
The electric motor's contacts and brushes just deteriorate from sitting unused, corrode or stick
Just sitting in the driveway shift from 2WD to 4high then to 4low and then back to 2WD, once a month, or when you remember
This will keep the motor clean so it will work when you actually need 4WD
You will also find out if it doesn't work...............so no surprises in the unexpected snow storm, lol

 

[DavidG]

Thanks @RonD - your info about the lone brown wire makes sense and I bought a new TCSM. However, I now have a different problem: the shaft on the transfer case that the transfer case motor slides onto is triangular shaped and and so is the female side on the transfer case motor itself. The problem is that the shaft on the transfer case is at one angle and the transfer case motor is at another and I can't figure out a way to manually turn the transfer case motor so that it aligns with the shaft.

I can, however, turn the shaft on the transfer case itself, but not far enough to match the angle on the shift motor. On the transfer case, there are marking for 2D, 4Hi and 4Lo and an arrow going in the counter-clockwise direction. So, as I turn the shaft from 2D, 4Hi is next and then 4Lo.

I can turn it all the way to 4Lo which is at about the 11 o'clock position and the female part on the shift motor is at about the 9 o'clock position. If there's a way to turn the shift motor manually, I could rotate the female part to the 11 o'clock position so that it matches up with the shaft, but I did not see a way to manually turn the motor.

Has anybody ran into this problem with the shift motor and the transfer case not aligned?

Thanks I appreciate any insights that you can provide.

David

 

[RonD]

Hook the shift motor up to truck and turn on the key, shift motor should automatically turn to 2WD if that's what the switch on dash is at

Also try selecting 4high, and then back to 2WD to make sure the new shift motor is responding

The shift motor doesn't need to be attached to the transfer case to work, to change positions
It needs no external grounding
If new shift motor doesn't move or doesn't match up in 2WD then it was assembled in correctly, return it

DO NOT try to turn shift motor manually, its a worm gear drive you will just strip the gear

Be careful turning the transfer case shift rod, there is a NEUTRAL and truck will roll away when you find it, its opposite 2H between 4H and 4L, just FYI

Turn transfer case shift rod back to 2WD, if that's what you selected on dash switch

 

[DavidG]

Thanks @RonD. I replaced the TCSM, but the problem remains in that the 4Hi and 4Lo lights flash and I can't get in to either mode.

Also, there was a point a while back that I could sometimes get the truck in to 4Hi, but definitely intermittent. It did seem to be more likely when the truck was cold, but not certain if that was all the time.

Do you think it could be the GEM module? If so, is there a way to test it?

You mentioned relays behind the GEM module - are there any other relays related to 4WD that are more easily accessible? Anything beside the GEM and relays that might be an issue?

Thanks very much for your help Ron!

 

[RonD]

No, those are the only two relays but they only power the motor part of the shift motor
They need Fuse 3 in the engine bay to be working
In the diagram they are the CW and CCW Relays(clockwise and counter clockwise)

GEM module, 4x4 part, usually doesn't fail, more likely to be a bad wire

Shift motor has 7 wires
2 power the motor, they come from the CW and CCW relays
Its a 12volt motor, so if one wire is + and the other - then motor turns CW, if one wire is - and other is + then motor turns CCW
Simple, work like power windows, window up and window down just reverse polarity

Other 5 wires are the Position Sensor, these run to the GEM
When you turn on the key the GEM powers up and Checks the Dash Switch position, AND THEN checks the shift motors position
If you had turned the dash switch from 2WD to 4H with KEY OFF, then with key on the GEM would activate the shift motor and turn transfer case to 4H

The Flashing 4WD lights mean either GEM tried to activate shift motor and sensors didn't change position(no movement) OR GEM can't tell the shift motor's position
Either could be one bad wire

4WD light could also flash if the dash switch was disconnected, of bad wire
It only has 2 wires, 5v IN and then 4v to 2v OUT
GEM sends the switch 5volts, if it gets back:
4volts then 2WD is selected
3volts is 4H
2volts is 4L

If you decide to dig into the dash then OHMs on the switch are
3,870 ohms for 2wd
1,090 ohms for 4wd high
357 ohms for 4wd low
Its a "pull down" circuit so OHMs are reversed of what you would think

Then test continuity of the 5 position wires to GEM connector

And the 2 motor wires to "relay box"

Also test voltage at GEM connectors and relay box, and Grounds

 

[DavidG]

Thanks @RonD. I checked fuse #3 and it's good and I replaced the dash switch, but the problem remains. Do I have to remove the GEM to get to the two relays or is "behind" mean toward the front of the truck?

In terms of this: "Then test continuity of the 5 position wires to GEM connector", do you mean from the switch to the GEM module e.g. test each wire from the switch to the corresponding wire on the GEM?

Thanks and I greatly appreciate your help!

David

 

[RonD]

GEM is mounted on drivers side of radio
Dual relay box is mounted on the firewall behind the radio

Yes, there are 5 position wires, get a jumper wire and connect 2 of the wires together on the shift motor connector
Then test continuity on those 2 wires at the GEM connector

GEM------------shift connector-(jumper)-shift connector-------------GEM

You are just making a "loop" so you can test both wires at one end

Test all 5 wires

 

[DavidG]

Does the GEM have anything to do with turn signals or hazard flashers? I'm asking because, in addition to the flashing 4Hi/4Lo lights, for some reason, both the turn signals and hazard flashers are now no longer working.

Also, I replaced the hazard flasher relay, but no change and I couldn't find the turn signal relay.

Thanks again @RonD!