Thank you very much, I will give it a shot tonight to see if I can get that fixed.
Rough Idle
Thread Starter
8th Gear
Joined: Apr 2007
Posts: 8
Likes: 0
From: Brighton MI
Rough Idle
I have owned my 95 vette for 3 weeks now, it has ran great until 2 days ago when I was waiting for a light to turn green. It starts to run rough, the rpm's drop like it's going to stall, and the service engine light comes on, but when I put in in N or start to drive, it runs fine, and the engine light goes right off. Any ideas? Thanks in advance.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Mate we need to know what that DTC is that got set with the Service Engine Soon light. Have a look below, grab your paper clip and let us know what ya get 
Remember to tell us which module number the DTCs appear in, all this info will be displayed on the digital panel where the speedo and other info would normally be.
On a 94/95 you can check the codes with a paper clip as follows:
You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.
The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:
Module "1" is still the CCM module.
Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.
Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).
Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- (the air bag control module) will be requested to show any codes.
Just like the 1990-1993 display, you read the codes on the speedometer (big) and read the module number on the trip odometer (small).
A series of dashed lines for instance “ - - -“ indicates no more stored codes for that module.
A code showing as “C12” for the CCM module (module #1) means no codes are stored. So C12 is a good thing to see.
Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.
Turn the ignition off and remove the short to restore normal operation.
To clear the codes,
1. With ignition "off" ground terminal #12 of the DLC (use bent paper clip to connect pin 4 to pin 12)
2. Turn ignition "on".
3. Press trip/odo button on the DIC until 1.7 appears in the trip
monitor area of the instrument cluster.
4. Press eng/met button on the DIC & hold until "---" appears in the
speedometer area of the cluster, this will clear CCM DTC'S.
To clear PCM/ECM codes do the following:
1. Press the trip reset button on the DIC until the desired system is displayed. In this case it will be 4.0.
2. Press trip/odo button on the DIC until the desired diagnostic mode(4.7) is displayed on the trip monitor area of the cluster.
3. Press & hold the eng/met button on the DIC until "---" is
displayed in the speedometer area of the cluster, this will clear PCM codes.
To clear ABS/ASR codes do the following:
Same as above but you’re looking for “9.7” on the trip odo
And here are the codes
1994-1995: Diagnostic Trouble Codes
DTC #11: Malfunction Indicator Lamp Circuit.
DTC #13: Bank #1 Heated Oxygen Sensor #1 Circuit:
DTC #14: Engine Coolant Temperature Sensor Circuit Voltage Low.
DTC #15: Engine Coolant Temperature Sensor Circuit Voltage High.
DTC #16: Distributor Ignition System Low Pulse.
DTC #18: Injector Circuit.
DTC #21: Throttle Position Sensor Circuit Voltage High.
DTC #22: Throttle Position Sensor Circuit Voltage Low.
DTC #23: Intake Temperature Sensor Circuit Voltage High.
DTC #24: Vehicle Speed Sensor Circuit.
DTC #25: Intake Air Temperature Sensor Circuit Voltage Low.
DTC #26: Evaporative Emission Canister Purge Solenoid Valve Circuit.
DTC #27: EGR Vacuum Control Signal Solenoid Valve Circuit.
DTC #28: Transmission Range Pressure Switch Assembly Fault.
DTC #29: Secondary Air Injection Pump Circuit.
DTC #32: Exhaust Gas Recalculation.
DTC #33: Manifold Absolute Pressure Sensor Circuit High.
DTC #34: Manifold Absolute Pressure Sensor Circuit Low.
DTC #36: Distributor Ignition System High Pulse.
DTC #37: Brake Switch Stuck On.
DTC #38: Brake Switch Stuck Off.
DTC #41: Ignition Control Circuit Open.
DTC #42: Ignition Control Circuit Shorted.
DTC #43: Knock Sensor Circuit.
DTC #44: Bank 1 LF Heated Oxygen Sensor #1 Circuit Lean.
DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich.
DTC #47: Knock Sensor Circuit Or Module Missing.
DTC #48: Mass Air Flow Sensor Circuit.
DTC #50: System Voltage Low.
DTC #51: EPROM Programming Error.
DTC #52: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #53: System Voltage Low.
DTC #55: Fuel Lean Monitor.
DTC #58: Transmission Fluid Temperature Sensor Circuit Low.
DTC #59: Transmission Fluid Temperature Sensor Circuit High.
DTC #62: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #63: Bank 2 RF Heated Oxygen Sensor #1 Circuit Open.
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
DTC #66: A/C Refrigerant Pressure Sensor Circuit Open.
DTC #67: A/C Pressure Sensor Circuit Sensor or A/C Clutch.
DTC #68: A/C Relay Circuit.
DTC #69: A /C Clutch Circuit.
DTC #70: A/C Clutch Relay Driver Circuit.
DTC #72: Vehicle Speed Sensor Loss.
DTC #73: Pressure Control Solenoid Circuit Current Error.
DTC #74: Traction Control System Circuit Low.
DTC #75: Transmission System Voltage Low
DTC #77: Primary Cooling Fan Relay Control Circuit.
DTC #78: Secondary Cooling Fan Relay Control Circuit.
DTC #79: Transmission Fluid Overtemp.
DTC #80: Transmission Component Slipping.
DTC #81: Transmission 2-3 Shift Solenoid Circuit.
DTC #82: Transmission 1-2 Shift Solenoid Circuit.
DTC #83: Torque Converter Solenoid Voltage High.
DTC #84: 3-2 Control Solenoid Circuit.(Auto Only).
DTC #84: 2nd And 3rd Gear Blockout Relay Control Circuit.
DTC #85: Transmission TCC Stock On.
DTC #90: Transmission TCC Solenoid Circuit.
DTC #91: One To Four Upshift Lamp(Manual Only).
DTC #97: VSS Output Circuit.
DTC #98: Tachometer Output Signal Voltage Wrong.
Remember to tell us which module number the DTCs appear in, all this info will be displayed on the digital panel where the speedo and other info would normally be.On a 94/95 you can check the codes with a paper clip as follows:
You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.
The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:
Module "1" is still the CCM module.
Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.
Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).
Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- (the air bag control module) will be requested to show any codes.
Just like the 1990-1993 display, you read the codes on the speedometer (big) and read the module number on the trip odometer (small).
A series of dashed lines for instance “ - - -“ indicates no more stored codes for that module.
A code showing as “C12” for the CCM module (module #1) means no codes are stored. So C12 is a good thing to see.
Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.
Turn the ignition off and remove the short to restore normal operation.
To clear the codes,
1. With ignition "off" ground terminal #12 of the DLC (use bent paper clip to connect pin 4 to pin 12)
2. Turn ignition "on".
3. Press trip/odo button on the DIC until 1.7 appears in the trip
monitor area of the instrument cluster.
4. Press eng/met button on the DIC & hold until "---" appears in the
speedometer area of the cluster, this will clear CCM DTC'S.
To clear PCM/ECM codes do the following:
1. Press the trip reset button on the DIC until the desired system is displayed. In this case it will be 4.0.
2. Press trip/odo button on the DIC until the desired diagnostic mode(4.7) is displayed on the trip monitor area of the cluster.
3. Press & hold the eng/met button on the DIC until "---" is
displayed in the speedometer area of the cluster, this will clear PCM codes.
To clear ABS/ASR codes do the following:
Same as above but you’re looking for “9.7” on the trip odo
And here are the codes
1994-1995: Diagnostic Trouble Codes
DTC #11: Malfunction Indicator Lamp Circuit.
DTC #13: Bank #1 Heated Oxygen Sensor #1 Circuit:
DTC #14: Engine Coolant Temperature Sensor Circuit Voltage Low.
DTC #15: Engine Coolant Temperature Sensor Circuit Voltage High.
DTC #16: Distributor Ignition System Low Pulse.
DTC #18: Injector Circuit.
DTC #21: Throttle Position Sensor Circuit Voltage High.
DTC #22: Throttle Position Sensor Circuit Voltage Low.
DTC #23: Intake Temperature Sensor Circuit Voltage High.
DTC #24: Vehicle Speed Sensor Circuit.
DTC #25: Intake Air Temperature Sensor Circuit Voltage Low.
DTC #26: Evaporative Emission Canister Purge Solenoid Valve Circuit.
DTC #27: EGR Vacuum Control Signal Solenoid Valve Circuit.
DTC #28: Transmission Range Pressure Switch Assembly Fault.
DTC #29: Secondary Air Injection Pump Circuit.
DTC #32: Exhaust Gas Recalculation.
DTC #33: Manifold Absolute Pressure Sensor Circuit High.
DTC #34: Manifold Absolute Pressure Sensor Circuit Low.
DTC #36: Distributor Ignition System High Pulse.
DTC #37: Brake Switch Stuck On.
DTC #38: Brake Switch Stuck Off.
DTC #41: Ignition Control Circuit Open.
DTC #42: Ignition Control Circuit Shorted.
DTC #43: Knock Sensor Circuit.
DTC #44: Bank 1 LF Heated Oxygen Sensor #1 Circuit Lean.
DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich.
DTC #47: Knock Sensor Circuit Or Module Missing.
DTC #48: Mass Air Flow Sensor Circuit.
DTC #50: System Voltage Low.
DTC #51: EPROM Programming Error.
DTC #52: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #53: System Voltage Low.
DTC #55: Fuel Lean Monitor.
DTC #58: Transmission Fluid Temperature Sensor Circuit Low.
DTC #59: Transmission Fluid Temperature Sensor Circuit High.
DTC #62: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #63: Bank 2 RF Heated Oxygen Sensor #1 Circuit Open.
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
DTC #66: A/C Refrigerant Pressure Sensor Circuit Open.
DTC #67: A/C Pressure Sensor Circuit Sensor or A/C Clutch.
DTC #68: A/C Relay Circuit.
DTC #69: A /C Clutch Circuit.
DTC #70: A/C Clutch Relay Driver Circuit.
DTC #72: Vehicle Speed Sensor Loss.
DTC #73: Pressure Control Solenoid Circuit Current Error.
DTC #74: Traction Control System Circuit Low.
DTC #75: Transmission System Voltage Low
DTC #77: Primary Cooling Fan Relay Control Circuit.
DTC #78: Secondary Cooling Fan Relay Control Circuit.
DTC #79: Transmission Fluid Overtemp.
DTC #80: Transmission Component Slipping.
DTC #81: Transmission 2-3 Shift Solenoid Circuit.
DTC #82: Transmission 1-2 Shift Solenoid Circuit.
DTC #83: Torque Converter Solenoid Voltage High.
DTC #84: 3-2 Control Solenoid Circuit.(Auto Only).
DTC #84: 2nd And 3rd Gear Blockout Relay Control Circuit.
DTC #85: Transmission TCC Stock On.
DTC #90: Transmission TCC Solenoid Circuit.
DTC #91: One To Four Upshift Lamp(Manual Only).
DTC #97: VSS Output Circuit.
DTC #98: Tachometer Output Signal Voltage Wrong.
Thread Starter
8th Gear
Joined: Apr 2007
Posts: 8
Likes: 0
From: Brighton MI
another ?
Another problem I am having is that my heater/ac control is stuck on defrost I believe. I am not getting any air on my feet or face when I push the button to switch. Any ideas? I do not have the auto climate control.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Its really easy mate, and in this case, its almost necessary anyway. You cant go wrong if you follow the instructions.
Here is a pic of the diagnostic link under the dash:
The one in the picture is from a 95 F-body, but it is basically the same connector. 4 is right above 12, and they are the 2 you need to connect together with a paper clip or something else metalic.
Here is a pic of the diagnostic link under the dash:
The one in the picture is from a 95 F-body, but it is basically the same connector. 4 is right above 12, and they are the 2 you need to connect together with a paper clip or something else metalic.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
If you look at this picture you can see the part im talking about, its abit hard to see in this pic but its all ive got at the moment.
Its located near the injectors for cyl 6 and 8.
(You DO NOT need to remove the rocker cover!!! That was just off when i took the pic)
Last edited by Casethecorvetteman; Apr 10, 2007 at 10:47 AM.
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Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Intermediate
Joined: Nov 2006
Posts: 33
Likes: 8
Mate we need to know what that DTC is that got set with the Service Engine Soon light. Have a look below, grab your paper clip and let us know what ya get Remember to tell us which module number the DTCs appear in, all this info will be displayed on the digital panel where the speedo and other info would normally be.
On a 94/95 you can check the codes with a paper clip as follows:
[B]You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.
The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:
Remember to tell us which module number the DTCs appear in, all this info will be displayed on the digital panel where the speedo and other info would normally be.On a 94/95 you can check the codes with a paper clip as follows:
[B]You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.
The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:
i have some weirdness on my 94 when trying the above. i'm trying to diagnose the problem from here: http://forums.corvetteforum.com/show....php?t=1692593
and when i short out 4 to 12 and turn on the ignition, everything powers up, the ses light comes on steady, and i get NOTHING read out, not even the c12. the speedo stays at 0, and no other fields are lit other than what is normally lit when turning on the key.
i tried cycling the odometer, the gauges button, the gas button, and all the others, and no changes was seen. the car runs pretty normally when cold, so i doubt the computer is dead.
is there some mode that the console has to be put in for this to work?
thanks,
charlie
