4WD Transfer Indicator Switch

[DougS]

99 SR5 3.4 auto

It appears that my transfer case top right switch is failed open. A jumper in the harness connection restores the VSV toggle from restraint to engage for the front actuator and lights up the dash symbol for four wheel drive. I may install a toggle switch manually operated from inside the cabin as a work around to the near hidden T case switch requiring me to butcher the tunnel or contort like Houdini from below....

My question is what functions do the two switches on the left side of the T case perform? Input to the ECU and transmission for shift points control?

 

[phattyduck]

My question is what functions do the two switches on the left side of the T case perform? Input to the ECU and transmission for shift points control?

One is the 4LO switch, used for transmission shifting (goes only to the ECU). One is for transfer case neutral - turns on the "AT/P" light on the dash if the transmission is in park and the transfer case is in Neutral (warns you that the parking pawl won't hold the vehicle).

-Charlie

 

[Bad Luck]

It appears that my transfer case top right switch is failed open. A jumper in the harness connection restores the VSV toggle from restraint to engage for the front actuator and lights up the dash symbol for four wheel drive. I may install a toggle switch manually operated from inside the cabin as a work around to the near hidden T case switch requiring me to butcher the tunnel or contort like Houdini from below....

My question is what functions do the two switches on the left side of the T case perform? Input to the ECU and transmission for shift points control?

If you unbolt the transmission crossmember you can lower the transmission enough to get to that transfer case switch FYI

 

[DougS]

more........

Thanks Charlie for that information on the other two switches and Bad Luck for your input. If the cross member is out of the way how low can you get the T case before something is binding or interfering at the fan end of the engine? I have just finished with the flex plate removal and replace, vacuum actuator remove, rebuild and install. It is a lot of ground time under the truck so I am really tempted to go through the tunnel wall with a cut off wheel. Or just go substitute manual with a toggle switch in the cabin. You guys probably hate that idea though........

 

[Bad Luck]

Thanks Charlie for that information on the other two switches and Bad Luck for your input. If the cross member is out of the way how low can you get the T case before something is binding or interfering at the fan end of the engine? I have just finished with the flex plate removal and replace, vacuum actuator remove, rebuild and install. It is a lot of ground time under the truck so I am really tempted to go through the tunnel wall with a cut off wheel. Or just go substitute manual with a toggle switch in the cabin. You guys probably hate that idea though........

Toggle switch will work as long as you know what the switch you are controlling is telling the vehicle to do and don’t forget to turn it on/off as necessary. I had mine sagged quite a bit. I think the limiting factor was the rack/crossmember by the rack coming in contact with the engine/transmission bell housing. I had to use an open end wrench and a few curse words to remove the switches when I was cleaning them for a 4wd issue. I supported the transfer case with a jack and removed the whole transmission crossmember, but I think just removing the transmission crossmember to frame bolts would be sufficient.

 

[alabamatoy]

So on a 99 4Rnr, MT, V6 SR5, *should* there be a low-range indicator light? 4X4 works, and there is a green indicator light when it goes into 4X4, but no indicator when it goes into 4L. I have confirmed my 2 (two!) transfer indicator switches are working correctly.

??

 

[phattyduck]

So on a 99 4Rnr, MT, V6 SR5, *should* there be a low-range indicator light? 4X4 works, and there is a green indicator light when it goes into 4X4, but no indicator when it goes into 4L. I have confirmed my 2 (two!) transfer indicator switches are working correctly.

??

No Low Range switch on the MT - that is only used for the ECU to control shift points on the J-shift case.

-Charlie

 

[alabamatoy]

No Low Range switch on the MT - that is only used for the ECU to control shift points on the J-shift case.

The ECU has no control of shift points on MT.....right? I confirmed that the drivers side normally open switch does indeed close on placing the xfer case in low range. The very hard to reach switch on the passenger side detects shift into 4X4. So yes, this is a low range switch on MT.

I rarely drive this truck, but wife was insisting there was a low range indicating light that's not working.

 

[TheDurk]

About four years ago I installed a manual toggle switch shorting out that switch where it lands on the relay in the passenger well (5-speed with J-shift) as a temporary fix. I was just going to wait until the weather warmed up to swap the switch. I know how to drop the tranny but I find I really like the manual switch. The 4x4 dash indicator tells you if it is engaged. The only thing that could go wrong is thinking you are in 4x4 when you actually have the TC in H2. It's not something I ever remember doing. I finally made the switch pretty instead on leaving it taped to my phone mount.

In the army they say there is nothing more permanent than a temporary installation.

 

[Gone4broke]

Does anyone know if the switch on the front diff for the ADD system is the same exact part as the reverse light switch or the transfer case switch?

I'm going insane trying to track down my issue.

No 4wd j shift 1997

 

[Riceye]

Does anyone know if the switch on the front diff for the ADD system is the same exact part as the reverse light switch or the transfer case switch?

I'm going insane trying to track down my issue.

No 4wd j shift 1997

I did a search and copy/pasted from an old similar thread. Not sure if they are the same parts, though.

*It is easily accessible at the rear of the front diff without removing the skids. Look for the two wire harness. While the switch should require a 27mm metric socket for removal, a shallow 1-1/16" socket worked just fine for me. You will lose a few drops of gear lube when you remove the old one, so be ready for that.

I replaced mine with a Dorman p/n 600-554.

 

[phattyduck]

Does anyone know if the switch on the front diff for the ADD system is the same exact part as the reverse light switch or the transfer case switch?

I'm going insane trying to track down my issue.

No 4wd j shift 1997

They all have different OEM part numbers, so unlikely.

-Charlie