1999 suburban wont go outa 4wd

120

Asked by Jun 23, 2014 at 10:36 PM

Question type: Maintenance & Repair

tranny went and tc was bad so i replaced them both not my truck is stuck in 4wd

UPDATE: took it to a transmission shop and they gave me the following codes, C0310 Motor A/B Circuit open C0323 Transfer
Case lock circuit low C0327 Encoder Circuit Extensive noise coming out of the transfer case will need another transfer case. so i
bought another case today and still the same problem will not go in to 2 High when you start the truck it goes to 4 high if you try
to put it in 2 H it will go to 4 low and you got to undo the battery to get it to reset back in to 4 high can some 1 please help me i
got over 2 grand in this

17 Answers

58,235

Have you tried to manually,shift actuator by hand?Take rod lose at transfer case,shift by hand,if it doe,s not work,you have a bad transfer case again.if it doe,s work change your actuator on transfer case.

1 out of 1 people think this is helpful.
120

do you mean the encoder motor on the transfer case i thought the actuator is on the front axle it shifts into 4hi 4low and all wheel drive if i put in 2h sounds like its shifting but just ends up in 4h or 4l wont stay in 2h im a women so dont know much but i have spent over 1900$$

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58,235

Yes you are right encoder tells it what ,to be in 4h 4l 2h.

1 out of 1 people think this is helpful.
58,235

Take it lose shift by hand,and if i would have payed that much my mechanic would be trouble shooting it.

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120

i have went through 3 different ones you can hear the motor switching gears but it trys to go in to 2high but wont let it i was wondering would one of the sensor's might be bad in the transfer case or the actuator on the front axle and i got a 4l60 E tranny and a np8 transfer case do i have vacuum lines on this truck and what else would make it not disengage from 4wd before this all happen i bought truck i dont think 4wd worked . and now i kinda wish it still didnt...PLEASE HELP SOMEONE lol

1 out of 1 people think this is helpful.
58,235

I think there may be relay,s for the encoder and the actuator,have they checked these?If you are having same problem,it,s not the tranfor case to start with.it has been with the truck the hole time...check for the relay,s and any wiring gone bad,.

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Best Answer
120

you dont have no idea where ? or if there is any vacuum lines

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58,235

Give me some time ,may be check this post tommorow i will give you more info after i do some searching on it ok : )

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120

ok thank you very much TST i will do so have a blessed night

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58,235

From what i have reseached so far is there are two thing,s that cause this,it is your encoder,or bad switch in the dash it self.That said i would have thought they may have changed the encoder,being you had it swapped so many time,s or did they use the origanal one?If it has been changed,as i said before problem has been with truck the whole time,check that dash 4x4 swicth.

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58,235

Encoder location

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120

i put a new switch in dash and new encoder motor same result im try to replace the TCCM today

1 out of 1 people think this is helpful.
58,235

Ok. good to know this,im not giving up,on it,but maybe that will fix you.Let me know im curious ; )

120

well tried to put in another TCCM and i put auto trec II fluid in the transfer case does the same thing goes in 4h and 4 low also in auto 4 wheel but i think auto is still 4 high so far i replaced the encoder motor TCCM i tried a new actuator but got same results so i took it back. does any 1 know if a np8 transfer case got vacuum lines

1 out of 1 people think this is helpful.
58,235

Ok, found you something you will want to check out,may help all so.This is NP8 tranfer case 101.it has hole lay out of it,with good info,so here ya go..www.chevyavalanchefanclub.com/cafcna/index.php?topic=41895.new.

1 out of 1 people think this is helpful.
120

Still same results some 1 please help me get my truck out of 4wd

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10

Hi If you are still on this site about your 4wd you are not alone- I have been throwing parts at mine as well- stuck in 4wd hi.. flashes but will not shift. I am thinking like you- vacuum.. I did find a deteriorated vacuum line this evening in the dark with a flashlight- will replace in the day light to morrow and see if that pulls it out of 4wd.. My vacuum is on the passenger side and could be a heater control- but the switch is electrical so where it comes off of might be the leak in the front axle.. we'll see thanks

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