1989 caprice check engine light

the check engine light is coming on on my 1989 caprice classic
using a code key i get code 12. does anyone know what this means?

I have a chilton's book here that says a code 12 is "No engine speed signal/diagnostic system functioning" I think it may have to do with the Transmission Converter Clutch (TCC) It engages when the car has reached a "highway" speed. It allows the torque converter to mechanically couple the engine to the transmission. When the brake pedal is pushed, or when the gas pedal is pushed harder, it disengages and goes back to the way it was. It almost feels like an overdrive gear.
Is it an intermittent problem? Or is it constant? Intermittant fault codes can be caused by loose or damaged wiring and connectors. Check the wiring for breaks or damage. Check the wiring connectors and make sure they are not corroded and that they are tight. Sometimes wiggling a poor connection while the engine is running will set an intermittant trouble code.
That's about all I can think of...

I have an 89 caprice also(not a classic though) and I am having a similar problem. We've taken it in and they say that nothing is wrong with the car and they offered to disable for us, but we just leave it so i still get it on highway trips

I had a problem with the TCC on my '86 caprice.It actually got bad enough that it would stay locked and would stall whenever I stopped. I had to manually shift the car into low 2 while stopping to get it to disengage. It's just a plug on the side of the tranny case, so I disconnected it, lost the feul milage, but it isn't that bad...

the check engine light is coming on on my 1989 caprice classic
using a code key i get code 12. does anyone know what this means?

Yes, it means the 'puter is working.

when you ground the ALDL (aka ALCL) diag port, the SES light will give the code 12 flashout 3 times, long pause then any stored codes 3 times, then finish up with 12 3 times.

I dont know what reader you have but it seems it cannot deal with sequential codes, which sucks, UNLESS you didnt count long enuf.

At any rate, a scan tool will show you what is stored and then we can proceed from there.

if you DIDNT get a code 12, id be worried.

To burnM: that explanation is ok, it means the engine is not running (no tach or engine speed signal, and the ECM is in fact working.)

The code 12 is the code indicating the functionality of the rpm signal from the distributor. It tells the computer that the engine is running, or being cranked. The rpm signal is used to control the speed of injection, comparison of tps, MAP etc. Ray

Well f**k me gently with a chainsaw...burnM got burned!!:)

oh like i said i have this problem with my 89 caprice and my friend is having it with his 92 Z34 lumina so its not that uncommon i suppose

What code comes out after the 12? Code twelve on an 89 Caprice is not, I repeat NOT a problem. As stated above it simply means that computer is working.

You need to wait and see what code(s) comes out after that and deal with those.

I cannot overstate the GM manual regarding code 12. If the engine light is on with the engine running, and the only code stored is a 12, it is NOT an all clear. I have personally repaired these types of vehicles by troubleshooting the code 12 to a REAL conclusion. It could be a filter, distributor, whatever. Code 12 is an rpm signal code. It shows up during a code check because the engine is off, and the key is on. Any doubters can get a manual and look it up themselves. Ray

RABarrett - Close but not quite. You are right that a code 12 could indicate a problem But only on a VIN Y 307 engined car, a station wagon in other words.

From my FSM No Engine Speed Reference - VIN 'Y' CARB
Indicates an open or ground in the distributor reference circuit. burnM had the right description as well.

However we still don't if the person with the problem is even following the right procedures to get the codes or exactly which vehicle they have.

I made the assumption from their car description that it was NOT a wagon. Thus code 12 should never show as a problem.

Lastly, in order for it to show as a stored code, they would have to see code 12 flashed 9 times.

Incorrect Olds breath! I spent 12 years w? Gm in driveability. Code 12, when referenced to the Code book is simple. No reference pulses to the ECM, regardless of the GM make, engine, or trans. Look it up. I spent those 12 years, and the following 10 years doing what others could not; fixing problems defying others' expertise. Some of those included the code 12, lighting the check engine light, no other codes stored. When I traced the rpm reference circuit, Hot Damn, the computer was receiving no reference pulses. It was just as if the damn computer was telling me that everything was fine, but the light was on! The fix? Locate the lost reference signal. The result? No more light, no more code set. Now unless you intend to attempt to try undoing 22 years EXPERIENCE, you might try listening to someone who has BEEN THERE. It got to the point where the CHEVY ZONE OFFICE, The BUICK, OLDS PONTIAC ZONE OFFICE, and the CADILLAC ZONE OFFICE was sending any and all problem cars to the dealership where I worked, in the Dallas/Ft. Worth area. I was buried in problem cars, and sent the results back to the zone offices in question, to be used for the rewriting of the driveability manuals. If the light is staying on w/ no other codes strored, you might consider the possibility that the code 12 is real. Ray

Incorrect Olds breath! I spent 12 years w? Gm in driveability. Code 12, when referenced to the Code book is simple. No reference pulses to the ECM, regardless of the GM make, engine, or trans. Look it up. I spent those 12 years, and the following 10 years doing what others could not; fixing problems defying others' expertise. Some of those included the code 12, lighting the check engine light, no other codes stored. When I traced the rpm reference circuit, Hot Damn, the computer was receiving no reference pulses. It was just as if the damn computer was telling me that everything was fine, but the light was on! The fix? Locate the lost reference signal. The result? No more light, no more code set. Now unless you intend to attempt to try undoing 22 years EXPERIENCE, you might try listening to someone who has BEEN THERE. It got to the point where the CHEVY ZONE OFFICE, The BUICK, OLDS PONTIAC ZONE OFFICE, and the CADILLAC ZONE OFFICE was sending any and all problem cars to the dealership where I worked, in the Dallas/Ft. Worth area. I was buried in problem cars, and sent the results back to the zone offices in question, to be used for the rewriting of the driveability manuals. If the light is staying on w/ no other codes strored, you might consider the possibility that the code 12 is real. Ray

will you guys chill? the original petitioner has never responded so we dont know what test proc was followed. however, by his use of the phrase 'code key' im thinking some walmart 'reader' was used and the instrs say to be KOEO.

A few points of order, the 89 CC did in fact have a Y code in sedan AND wagon form - wagon it was the only motor, sedan it was a horrible choice of an option and not avail in CA. regardless, unless the harness is bit in two, its impossible to get no tach from the EST without loss of the EST itself which throws other codes

so until the poster does what I asked and uses a real scan tool to find any and all numbers, we need to save the diagnosis

ps - olds breath?

I'm guessing olds breath refers to the 307 being an oldsmobile engine. And yes, cap clas did come with that engine in sedan form. My friend has one. I don't think those engines are that bad.
I don't think we should be arguing though, bpeesy seems to have disappeared.

RABarrett I'm sorry if I've struck a nerve. Not my intention at all. Just trying to help out where I can that's all. With all of your experience you are probably correct.

I am reading my General Motors B Carline Service Manual 1989 purchased new from Helm about 3-4 years ago. This manual lists Code 12 only under the section for Driveability and Emissions 5.0L(VIN Y). It states that it is no reference pulse from the distributor as you said.

However, the Driveability and Emissions sections for 4.3L, 5.0L and 5.7L start with Code 13. No mention of Code 12.

As far as engine availability goes guys. It is my impression that the VIN Y 307 Olds engines were only available in 1989 in a wagon. They may have been available in other years in the sedans. But B-car wagons were the only cars to get the VIN Y 307 I believe in 1989.

Just reading all these posts and have a question about ses codes. I used a wire to jump the ground and the hole next to it figure what codes it was throwing out. I got a code 24. What could be wrong, if anything. The light only comes on when I go over 60 for longer than a few seconds or if over 60 and then slow down. thanks for the help.

Andy

CODE 24 = Vehicle Speed Sensor (VSS)
No vehicle speed present during road/load deceleration. NO Vehicle Speed Indication.

Fun thread.