having vacuum issues with my 4x4 and i checked my obdII on my 96 blazer and i think i keeping getting the same code when grounding pin 13. What happens is i'll put my car on and after 3 secondsall 3 lights (2h, 4h, and 4l) flash onceand then turn off. After that the same 3 lights will flash but 4 or 5 seconds apart andwont stop. These are all one blink flashes then a 5 second delay in between. Any idea what code this can be and what i should do to fix?

 

Sounds like DTC 1.

 

I see the way to clear the code as "This DTC will clear when the voltage supply failure has been corrected and the ignition switch has been cycled five times" but does that fix the problem? If not, how would i go about fixing the problem?

Also would DTC1 cause me not to get any vacuum supply because ive checked everythign except for holes in the hoses and im not getting any vacuum to my actuator.

 

It should not cause you to not get vacuum supply to the front axle so long as the transfer case is actually completing the shift.

 

So i guessthis code isnt whats causing myvacuum supply shortage then? I am hearing the click when i put itin and out of 2 and 4 wheel... im just not getting any vacuum... How do i know if its completing the shift?

Also if this isn't causing the problem then it has to be the some kind of hose problem. The actuator, transfer case, andtcase switch are all fine so it must be a proble with one of the three lines. Any tips on how to check these lines for dryrot? These lines run up very tight places and i dont see how i canpossibly inspect them from the tcase switch to where they go. Any tips on how i can do this?

 

Do you feel the torque multiplication when in 4LO? That is the easiest way to make sure that the transfer case is actually completing the shift. You can also check to see if the front driveshaft is engaged by attempting to turn the driveshaft once you have shifted into 4HI or 4LO. This does not work with the NV236 (auto4wd switch option) transfer case though, but you have the NV233.

How have you verified that the t-case vacuum switch is not the problem? Have you gone through all of the hoses, making sure that all of them are good and sealed up?

 

I definitely feel the torque when shifting into 4lo, but i only get power to the rear wheel, but the torque is most definitely there.

Not sure what kind of transfer case i have, but the drive shaft does lock when putting the car in 4h or 4l. It moves feely when its in 2h.

I'm positive it's not the switch because i just put in a new one yesterday and still no vacuum. Its also not the actuator itself... no holes and holds the vacuum (if there was one).

I think this leaves me to the hoses since i've tried everything else. Theres nothing i can visually see as being wrong with them, but ive only checked them near the switch by the transfer case and on top of the engine. I have checked where they run down from the engine by the transmission and wherever else they go. Is there an easy way to check these hoses because they seem like theyre in the tightest areas. I'd like to check every spot but how is that even possible? Will i have to rip all three hoses out and check that way?

 

Do you have vacuum source to the switch in the transfer case? You can check this by disconnecting it. One of the lines should have vacuum. Also, there should be only one way that the vacuum fitting (three hose connection) fits onto the switch.

 

I pulled the plug and there is vacuum coming from one of those hoses but its very little. Any idea how strong it should be without me getting some kind of pressure guage to test? Its not very strong...

Oh and theres also a little transmissionoil that initially leaks when i pulled the plug. Is this normal?... its hooked up to the switchcorrectly.

 

Transmission fluid in the vac lines is not good at all. That is a sign that you have way too much fluid in the transfer case. I would at the very least pull the fill plug (upper plug) on the back of the transfer case. If fluid comes pouring out, then you need to pull the transfer case and replace the input seal.

Once you verify vacuum at the connector on the transfer case, you need to move forward. You should follow the vac line to the 4wd actuator and make sure that it is not damaged. If you do not have vacuum up to the actuator when in either 4HI or 4LO, then there is either a problem with the vacuum line or a problem with the switch.