Code Key BUT NO Code book

Can someone tell me where i can download a code book for GM. I have a 1991 Astro Van AWD.

try a search online for gm odb1 codes.
Or for about 12 bucks you can get a haynes manual for your van.
Or, post the code you are getting. A bunch of folks here on the forum have manuals and can tell you what the code is for.

I have all of these codes for an 89 B-body. The van should be very similiar if not identical.

CODE AND CIRCUIT POSSIBLE CAUSE

CODE 12 = System check
Indicates that the ECM is functioning.

CODE 12 = No Engine Speed Reference - VIN 'Y' CARB
Indicates an open or ground in the distributor reference circuit.

CODE 13 = OPEN Oxygen Sensor (O2)
Indicates that the oxygen sensor circuit circuit or sensor was open for one minute while off idle.

CODE 14 = Coolant Sensor (CTS)
Sets if the sensor or signal line are grounded for 3 seconds. HIGH Temperature indication.

CODE 15 = Coolant Sensor (CTS)
Sets if the sensor wires or connections are open for 3 seconds. LOW Temperature indication.

CODE 21 = Throttle Position Sensor (TPS)
TPS voltage of more than 2.5 volts for 3 seconds at an engine speed less than 1200 rpm. HIGH Voltage Signal.

CODE 22 = Throttle Position Sensor (TPS)
A shorted to ground or open signal circuit will set code in 3 seconds. LOW Voltage Signal.

CODE 23 = Manifold Air Temperature Sensor (MAT)
Sets if the sensor wires or connections are open for 3 seconds or Intake Air Temperature (IAT) LOW Temperature indication.

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

CODE 25 = Manifold Air Temperature Sensor (MAT)
Sets if the sensor or signal line are grounded for 3 seconds. Or Intake Air Temperature (IAT)
HIGH Temperature indication.

CODE 32 = Exhaust Gas Recirculation (EGR)
OR Vacuum switch shorted to ground on start up. Switch not closed after the ECM has commanded EGR for a specified period of time OR EGR solenoid circuit open for a specified period of time.

CODE 33 = Manifold Absolute Pressure (MAP)
MAP sensor output too high for 5 seconds or an open circuit. LOW Vacuum.

CODE 34 = Manifold Absolute Pressure (MAP)
Low or no output from sensor with engine running. HIGH Vacuum.
CODE 35 = Idle Air Control (IAC)
IAC error.

CODE 42 = Electronic Spark Timing (EST)
ECM has seen an open or grounded EST or Bypass circuit.

CODE 43 = Electronic Spark Control (ESC)
Signal to the ECM has remained low for too long or the system has failed a functional check.

CODE 44 = LEAN Exhaust Indication
If voltage to oxygen sensor remains BELOW .2v for more than 20 seconds code is set.

CODE 45 = RICH Exhaust Indication
If voltage to oxygen sensor remains ABOVE .7v for more than 1 minute code is set.

CODE 51 = PROM - Faulty MEM-CAL or ECM.

CODE 52 = Faulty or missing CAL-PACK.

CODE 53 = System overvoltage
Indication of a faulty alternator or regulator. Camaro/Firebird uses a Code 53 for Vehicle Anti-Theft System (VATS).

CODE 54 = Low Voltage To Fuel Pump
Sets when the fuel pump voltage is less than 2 volts when reference pulses are being received.

CODE 55 = Faulty ECM

The list CD smalley posted is mostly standard for GM vehicles from '81 - '94 or so. There were some changes over the years, but for example a code 13 has ALWAYS been for the O2 sensor, 14-15 have ALWAYS been the coolant sensor, 21-22 have ALWAYS been the TPS, etc., until the four digit OBD2 codes started around '94. That list pretty much applies to your Astro.

Are you getting a specific code? Post it, along with your symptoms, and I can probably help.

try a search online for gm odb1 codes.
Or for about 12 bucks you can get a haynes manual for your van.
Or, post the code you are getting. A bunch of folks here on the forum have manuals and can tell you what the code is for.



I have a code key i got from Autozone. My question is i have a 1991 Astro Van AWD but were do i put the key to get the code's. Which pin do i put the key to.

Are you getting a specific code? Post it, along with your symptoms, and I can probably help.


I have not done a code test yet. But when i start the engine and drive to town it does alright till it warm's up then it start's to bog down when you give it gas. Even at at stop sign after taking off it will bog down. So i let up on the gas peddle then it stop's boging down. And then it run's fine.

This sounds like carbon build up in the engine. Probably in the the throttle body as well.
Is your service engine light on, or did it come on at some point?
If the SES light never lit up, no code is stored.
if that's the case the problem is either vacuum or fuel related.

Well i found a broken hose to the PVC valve. Replaced it run's a little better. And no check enginev light come's on and never has. I know it need's a tuneup bad i think that is where it is.

Well found another problem. My PCV vacum is not working . I think carbon is blocking it. Try to blow it out with air hose and that did not work. Is it hard to take the TBI off to clean it out. Or is the an easier way.

The TBI is pretty easy to take off. Best way I have found to clean them goes simething like this:

Buy rebuild kit for said TBI - gaskets, screens, o-rings etc.

Buy gallon of carb cleaner. Advance Auto sells a gall on can of carb cleaner.

Remove and disassemble the TBI unit

Soak the TBI and it's pieces, excluding the injectors, in the colution overnight.

Clean up TBI unit and pieces the next day with spray carb cleaner and some q-tips to get the tight places.

Reassemble and reinstall.

I'd get a Haynes manual as well.They have a pretty good write up and photos of the TBI rebuild.
You'll need torx (star) drivers for some of the screws. Also make sure to get new O rings for the fuel lines. My rebuild gasket kit didn't have them. Had to make another trip to the store.
You may have to do a little scraping to get the carbon out of the PCV port on the throttle body.

Thank's everyone for the help.