GMC Repair: transfer case relay or 4 wheel drive fuse?, e mail address, wheel positions

Question
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Followup To
Question -
Is there such a thing as a transfercase relay, or a 4 wheel drive fuse?  the 4 wheel drive indicator light isn't coming on to show that it's locked in, i was wondering if there is a fuse or a sensor that could be burnt.  The 4 wheel drive seems like it is partially engaging, but i think maybe it's not locking the hubs.  Any ideas?  It's a 1988 GMC sierra. thanks
Answer -
FIRST let's determine what system for engagement you have.

Do you have the MANUAL shift lever on the floor or it it all push button automatic ?.

it's a a shift lever on the floor, so sorry, i guess that would help, huh? :)




autohelp

Answer
You would be amazed at some of the questions I get. I got several who said that their 4 wheel drive does not work only to find out they don't have 4 wheel drive. Makes you want to scream.



OK, There IS an electrical shift light indicator located next to the shift lever that controls the lights on the display panel.

There are 2 components that LOCK the axles together and one to LOCK the front differential.


Look under the hood, just in back of the right front haed lights and you will see a vacuum operated diaphram that has 1 or 2 vacuum lines attached to it as well as a cable that goes down into the front axle engagement housing mechanism.


manipulate the shift lever from the 4 wheel positions and back to the 2 whell positions and see if the above siad diaphram under the hood engages and disengages and let me know.


Some models have an electrical indicator switch mounted also within the front axle engagement housing mechanism.


Some models have a 2 wire engagement THERMAL BULB that when you shift into 4 wheel drive this thermal bulb which is mounted in the front axle EXPANDS internally (like blowing up a balloon) and this expansion forces a pin to engage to lock the front differentail.



If you have an e-mail address I can e-mail you some specific diagrams so you can SEE what your looking for.



Contact me at:


meperganfortis@msn.com



And I will scan and e-mail the pictures.



autohelp