can anyone tell me what 12 and 21 codes are on my ram pickup

[BigBlockSam]

hey guys . my 1994 doge ram 3500 8.0  v10 pickup is revving real hi at start up and when ever it fells like it . i did the key  think  with the check engine light and i get code 12 and code 21 . can anybody here tell me what they mean . it's also sucking up  a lot of gas. 

[Todd Wilson]

hey guys . my 1994 doge ram 3500 8.0  v10 pickup is revving real hi at start up and when ever it fells like it . i did the key  think  with the check engine light and i get code 12 and code 21 . can anybody here tell me what they mean . it's also sucking up  a lot of gas. 

12 =  Battery disconnect in the last 50 starts


21 = O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions.


V10 = sucking up a lot of gas......


Todd

[BigBlockSam]

thanks Todd i'm gonna test that o2 sensor .

i've owned this truck since new 18 years . she's always been my soldier and thirsty  but not like this . i need a gas tanker behind me to keep her going now .  thanks again

[Todd Wilson]

Let us know what you find out so we can learn from it.  It may be O2 time.


Todd

[BigBlockSam]

that would be ok . cheap fix . some sensors get expensive 

[BigBlockSam]

Hey Todd , here's the deal . the right side o2 sensor was shorted out inside. read max volts. i changed it and now it is running less rich and the rpms came done but now the rpm's are up again and i get code 33   

does anyone know what code 33 is on my 1994 ram 3500 dually with the v10

[Todd Wilson]

   Code 33

AC clutch relay circuit - Short or open in the AC clutch circuit.


Todd

[A383Wing]

and if you don't have factory AC in truck, that code will come back all the time...ignore it if this is the case

I get codes for AC & speed control circuit on my reliant...it does not have those items

Bryan

[BigBlockSam]

ac works fine but some time at idle the rpms go up to 2000 then down to 1400. they should be at 800. 

[Cooter]

ac works fine but some time at idle the rpms go up to 2000 then down to 1400. they should be at 800. 

Not when running the A/C it won't....See, when the A/C is on, the idle air stepper motor kicks idle up to compensate for drag on engine from A/C Compressor.
up and down, up and down....

[Indygenerallee]

Vacuum leak!? I can't remember if that intake has a lower end gasket as such on a magnum 5.2 and 5.9 could not tell it was blown until you removed intake,

[gtx6970]

how many miles on the unit?

V10's were notorius for lower intake gasket leaks causing a lean idle or vacuum leak

[BigBlockSam]

i did the intake leak many years back . this thing runs fine for weeks , then i'll start it and the rpms go high . didn't do it much during the colder weather . i'm thinking maybe the speed throttle censor .it does it with the air on or off . i'm confused 

[Todd Wilson]

How old is your battery?  They say Ram's PCM can freak out when batteries are getting older. Sometimes the battery can start the truck with no troubles but is low enough in voltage to freak things out.


Todd

[BigBlockSam]

good batt 2 years old . it's almost like it had an old style  choke . i start it and the rpms go high . every once and a while i can kick it off

[A383Wing]

I think ya got a dirty IAC motor or one that is sticking...

Bryan

[BigBlockSam]

what is a IAC motor

[moparstuart]

idle air controller     it idles your motor up alittle when a/c is turned on to counter the  strain of the a/c compressor on the motor .

[BigBlockSam]

that sounds like it could be it . is there only one on my truck and can you they me where it is located . i'm so much better with the old cars then these newer ones .

thanks for all your help i've been fighting this problem for  the last year .cause it comes and goes 

[Indygenerallee]

round cylinder shape and its on the throttle body and should have a oval electrical connector and it is usually held in with 2 torx bolts. with a O ring gasket, pull it out and clean it off with some throttle body cleaner, usually pretty carboned up.

[BigBlockSam]

thanks bro gonna look at it tomorrow 

[BigBlockSam]

we have a winner Bryan was right . she's running great . no more idle up and down . better gas miliage , still sucks . she's running the best she has in a while . to bad i searching for a 2009 or 2010 crew cab now . thanks  for all the help guys . 

[ACUDANUT]

I agree with the above...I can't believe a 94 Ram is still on the road.  Mine died around 7 years ago. IMO it was a Piece of junk.

[BigBlockSam]

i luv my truck . i've owned it for 18 . bought it new and she never let me down . gonna buy a newer ram truck

[ACUDANUT]

My Transmission was rebuilt twice. The paint flakes off and the dash almost fell to the floor.