MonteCarloSS.com
MonteCarloSS.com

CELEBRATING 20 YEARS!

Previous Thread
Next Thread
Print Thread
#1067930 - 09/12/20 06:05 AM Help with Code 12  
Joined: Sep 2020
Posts: 5
felkermick Offline
New Member
felkermick  Offline
New Member

Joined: Sep 2020
Posts: 5
Warsaw IN
I recently purchased a 1986 SS that has 9800 miles on it and was well taken care of. When I purchased this Monte it had the check engine light on, and I jumped out AB pins and constantly got a 1 flash followed by 2 flashes over and over again. I looked that code up and it says basically there are no stored codes on my car, yet the check engine light is on. Car seems to run fine when driving and idling(sometimes dies when idling when stopped and in drive rpm drop below 300 when hot). I removed the negative battery cable lead for about a min or two and that did not clear the service engine soon light. My car has a few upgrades, it looks like it has electronic distributor and Edelbrock 4 barrel carb. Other than that she is stock. I can't seem to figure out what could be causing the Service Engine Light (Code 12). Again I let it blink when I jumped AB for over 2 min and it only ever blinked the code 12. Thanks for any help here.

#1067931 - 09/12/20 03:06 PM Re: Help with Code 12 [Re: felkermick]  
Joined: May 2004
Posts: 983
BladeOfAnduril27 Online content
15+ Year
BladeOfAnduril27  Online Content
15+ Year
Member

Joined: May 2004
Posts: 983
Doylestown, PA
Welcome to the forum.

It's going to flash code 12 three times, then any actual codes that are stored. Each code will flash 3 times, then code 12 will repeat at the end of the readout.

I can tell you right now that your light is on because of the Edelbrock and possibly the distributor if it's not the stock one. These cars came with a computer-controlled distributor and computer-controlled quadra-jet carb. If either of those are removed, it basically breaks the CCC system. What you do next will depend on what direction you want to go with the car. If it's truly 9800 miles, you may want to keep it original. In that case I would suggest reverting to a stock CCC carb/distributor. If you prefer, you can remove the CCC system and emissions components completely, depending on how concerned you are with local legal requirements for inspection, etc... If you choose to go that route, you will lose transmission converter lockup unless you install a kit to replace that functionality.


~ Matt H.

1988 Monte Carlo SS w/ T-tops, White with gray int, 350, Summit cam, World Torquer S/R heads, Holley St. Dominator intake, Edelbrock 600cfm carb, Champion 3-row alum radiator, ramchargers, 200-r4 with CK Shift Kit, billet servo, 2200 stall, Afterburner headers, Pypes 2.5" with x-pipe, Violator mufflers (stock exit), S10 front brake swap.
#1067932 - 09/12/20 03:18 PM Re: Help with Code 12 [Re: felkermick]  
Joined: May 2000
Posts: 1,858
BadSS Offline
20+ Year
BadSS  Offline
20+ Year
Member

Joined: May 2000
Posts: 1,858
Pearl, MS, 39208
If there is no check engine light on the code 12 means there is communication with the diagnostic port and since there are no other codes, all is well.

If the check engine light is on and all you get is a code 12 that means there is a communication problem with the computer. It could be a number of things, including up to a bad ECM. In your case since the computer carb has been replaced with a Edelbrock there's no feed from the computer carb and possibly they disconnected all the computer controlled wiring under the hood.

Does it have a vacuum advance "pod" on the distributor or is it a full electronic distributor? If it doesn't have a vacuum advanced distributor and still has the stock computer controlled distributor, it will go into limp home mode. If so, that's why it dies at times - the only amount of timing you have with the computer controlled distributor is the base timing - typically 6-10 degrees when everything is working, but they may have jacked the base timing up enough so it'll run.

Let us know which distributor you have and whether or not the computer controlled carb came with the car when you bought it.

Edit - started typing before Matt's response - lol

#1067933 - 09/12/20 03:35 PM Re: Help with Code 12 [Re: felkermick]  
Joined: May 2007
Posts: 5,026
Buick Runner Offline
10+ Year
Buick Runner  Offline
10+ Year
Member

Joined: May 2007
Posts: 5,026
Dharma station 1 the Hydra
Pretty simple, the Eddy carb is not compatible with car as it lacks computer provisions like every aftermarket carb and is not an upgrade over the factory E4ME Quadrajet carburetor. The stock carburetor has a air fuel mixture control solenoid and a throttle position sensor, which every aftermarket carb lacks. The factory computer system is all or nothing, remove any part and it goes into limp mode.

This is a common problems with G bodies, a previous owner hacks up the car and then sells the basketcase to an unsuspecting buyer. Even if you replace the carb with a correct factory one, there may be other strange modifications and Jerry rigging that will need to be repaired correctly. There is not much we can help you with over the net as it would take a expert to look over the car in person to see if there are any more Jerry rigging in the car. We can't examine the car over the net. Normal idle RPM is 2,200 cold, 600 hot in gear, 300 is way too low.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes, and Jmod.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1067937 - 09/12/20 10:55 PM Re: Help with Code 12 [Re: felkermick]  
Joined: Feb 2020
Posts: 528
88ssBrent Online content
Member
88ssBrent  Online Content
Member

Joined: Feb 2020
Posts: 528
Friendsville
http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=245007#Post245007

I feel that this link would be a good place to start for the problems your having. You are just going to have to make the decision if you want to go back to stock feed back carb or move forward with doing away with everything. Like stated above its all or nothing.

I really like the ccc system. I deal with programmable logic control (plc) on a daily basis so I find the ccc very interesting as it a lot alike (the inputs, the computer (brain), and outputs). I can only imagine at the time how excited g.m. engineers were when they created it in its infancy.

With that said, I'm sure at some point I will get away from it because it does have some limitations.

If I were in your shoes I would probably go the route I posted above and do away with the system. I think it would be the easier route without knowing what is there and what is not and what all has been done by previous owner. Good luck.

#1067941 - 09/13/20 12:28 AM Re: Help with Code 12 [Re: 88ssBrent]  
Joined: Sep 2020
Posts: 5
felkermick Offline
New Member
felkermick  Offline
New Member

Joined: Sep 2020
Posts: 5
Warsaw IN
Originally Posted by 88ssBrent
http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=245007#Post245007

I feel that this link would be a good place to start for the problems your having. You are just going to have to make the decision if you want to go back to stock feed back carb or move forward with doing away with everything. Like stated above its all or nothing.

I really like the ccc system. I deal with programmable logic control (plc) on a daily basis so I find the ccc very interesting as it a lot alike (the inputs, the computer (brain), and outputs). I can only imagine at the time how excited g.m. engineers were when they created it in its infancy.

With that said, I'm sure at some point I will get away from it because it does have some limitations.

If I were in your shoes I would probably go the route I posted above and do away with the system. I think it would be the easier route without knowing what is there and what is not and what all has been done by previous owner. Good luck.


I'm gonna see what a local repair shop thinks ... they are pretty good working on older vehicles. I'll forward this info to them and drop off my car see what exactly was done by the previous owner. I may go back to the Quadrajet carb as I'd rather be stock in the 1st place. Thanks for information it's gonn take a few weeks I think to get car into shop and figure out what changes were made here.

Last edited by felkermick; 09/13/20 12:31 AM. Reason: spelling
#1067945 - 09/13/20 01:08 AM Re: Help with Code 12 [Re: felkermick]  
Joined: Dec 1999
Posts: 11,898
86ttop Online grandpa
20+ Year
86ttop  Online Grandpa
20+ Year
Member

Joined: Dec 1999
Posts: 11,898
Brooksville, Fl
the stock quadrajet carb part number stamped vertically on the drivers side is 17086003, good luck!!


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs
#1067948 - 09/13/20 03:24 AM Re: Help with Code 12 [Re: felkermick]  
Joined: Dec 2005
Posts: 2,752
84LS1T56SS Offline
Member
84LS1T56SS  Offline
Member

Joined: Dec 2005
Posts: 2,752
Central, Arkansas
There just happens to be a NOS carb on ebay right now.



85 MCSS, 02 5.3/4L60E stock daily driver,84 MCSS, Another stock 5.3/60E.

Random Images
500/thumbs/MC_lowered.jpg
by tunit
500/thumbs/downsized_0402121841.jpg
by blkcharlotteman
852/thumbs/mont_and_road_runner_3.jpg
by PoorBoysRacing
1084/thumbs/1318197026021.jpg
by 87SSon6s
500/thumbs/IMG_1195resize.jpg
by monte_mike
Help MonteCarloSS.com


Recent Contributors
86BlackSuperSport
dns87ss
Authorized Vendors
Tell them you saw it
on MonteCarloSS.com!


CustomMonteSSParts.com
Dixie Monte Carlo Depot
GSI Interiors
HRpartsNstuff
Mikes Montes
Savitske Classic & Custom
Powered by UBB.threads™ PHP Forum Software 7.6.0