Engine/Transmission (1998.5 - 2002) 4wd light on after transmission fix

[ASimpson]

had new converter installed got my truck back and had to use 4wd. ever since my 4wd light comes on or flashes on and off while driving. any ideas? thanks

 

[LOtero]

check your wiring Its easy to pinch something when all your attention is going twards the 200lb trans, possibly shorting when your hitting bumps causing the light to come on.

 

[steved]

Since it is an 01, I'll assume it still has a CAD.



Since the vacuum hoses that engage/disengage the CAD in front axle (where the 4wd light switch is located) go across the transmission crossmember, they might have broken/crushed/disconnected a vaccum line... I would suspect that before a broken wire since the light needs 12 volt to activate (not a completion to ground type)...



Start by checking the vaccum lines... one pulls it in, the other pulls it out.



steved

 

[ASimpson]

Thanks Guys I Will Check Tonight.

 

[steved]

I also forgot to point out the switch for the 4wd indicator light is also located in the CAD shift housing on the front axle...



steved

 

[zstroken]

I am betting he got vacuum lines reversed or something. It happened to me once. I put it in 4wd and the light went off, put it in 2h and it came back on.

 

[steved]

I'm guessing a disconnected or broken line somewhere...



steved

 

[ASimpson]

My Light Comes On When I Put It In 4wd And Goes Out When I Take It Out Of 4wd But It Takes Longer For The Light To Go Out Now. Used To Just Bump The Throttle After Shifting Back Into 2wd And The Light Would Go Out Now I Might Have To Back Up Or Bump The Throttle 4 Or 5 Times Couldnt Find Any Loose Vacuum Lines Or Elec. Connectors Anyone Know If The Switch Can Be Bought At Parts Store Or Is It A Dealer Item. I Had To Replace A Switch Like That On A S-10 Once Before With Sort Of The Same Symptoms. Thanks Adam

 

[steved]

My Light Comes On When I Put It In 4wd And Goes Out When I Take It Out Of 4wd But It Takes Longer For The Light To Go Out Now. Used To Just Bump The Throttle After Shifting Back Into 2wd And The Light Would Go Out Now I Might Have To Back Up Or Bump The Throttle 4 Or 5 Times Couldnt Find Any Loose Vacuum Lines Or Elec. Connectors Anyone Know If The Switch Can Be Bought At Parts Store Or Is It A Dealer Item. I Had To Replace A Switch Like That On A S-10 Once Before With Sort Of The Same Symptoms. Thanks Adam

Sounds like the vacuum diaphram (the actual CAD mechanism that engages/disenges the front axle) has a leak... you can get a replacement part from DC... it's the thing the vaccum line go to on the front axle...



To diagnose it, take one of the vacuum lines off the diaphram. Use a short piece of hose to blow into the diaphram... if you can blow air through the hose (like it would never stop), then the diaphram actuator is bad. It might not be like blowing through a straw (remember the vacuum system on these trucks doesn't have a lot of volume), so even a small leak can cause issues.



steved

 

[ASimpson]

i think i figured this one out. no idea how it happened either. on the front axle where the switch and stuff is there is a disc shaped object that the vacum lines go into it seems to be threaded into the cad or whatever it screws into . it had come loose maybe a 1/4 of a turn tightened it up and no problem since. lets hope it stays that way. thanks to everyone for their replies. ya gotta love this place.