I have a 1991 pickup and when i bough the truck the owner said i had to turn a switch on every time i put it into 4 wheel drive. the switch is located on the left side of the steering wheel and has a red light that glows when the switch is on. so as he told me to i do, but if i turn the switch on if its not in 4 wheel drive it makes a squealing noise. what the heck is this switch for????

 

It ain't factory, I can tell you that much ... The only factory switch that looks anything like you describe is the clutch-start-cancel (which is what it says on it) and it wouldn't make anything make a noise for sure.

 

Does it have ADD..?

 

Automatic Differential Disconnect?.....i have no clue , should it?

 

No does the truck have ADD? (Attention Deficit Disorder)



















I'm super funny I know. haha

 

i thought so....

 

i just checked, by the look of the hubs it does......can someone explain to me what ADD does and why it would squeal if its not in 4WD

 

as well as should all 91's have this?

 

No, some came with manual locking hubs which must be engaged by turning a dial on each hub.

 

sweet...thanks guys

 

I knew that was coming ...

 

You should still find out what that switch does, because as others have mentioned, it's not stock. Follow the wires from the switch to see where they go.

 

where is the squealing noise coming from? wonder if it is a homebrewer e-locker set up...

 

Trace the wires. Nothing in the front end should squeal while in 4wd....

You probibly have the A.D.D and your hubs are just flanges... Mine were, till I swapped in manual hubs.

 

no...it squeels in 2wd if i turn the switch on....it doesnt make any noise while in 4wd

 

 

!!!I have this same switch on my truck and i was so confused because it never does anything. Course my 92 has a SA. Im glad i saw this because i want to know too