Today I attempted to find out what is wrong with my 1991 Corvette. I grounded Pin G to A to receive a diagnostic reading on the speedometer display. There were 5 modules to choose from; while scrolling through the trip odometer with the trip button the following displayed: 1.1, 1.2, 1.3, 1.4, and 1.7.
Below are the resulting codes per each module:

1.1 C12

1.2 01 17.6
02 0
03 162
04 0
05 0
06 211
07 12.7
08 12.1
09 69
10 69
11 69
12 74
13 107
92A0235

1.3 01 1
02-14 0

1.4 01

1.7 _ _ _


Any thoughts as to what the codes reveal in modules 2 through 4?

 

These are all diagnostic codes. You can even check a lot of your systems..horns, lights, pass-key resistance ect using your trip cluster buttons when in this mode. It's been a while since I've done it, but your numbers all look good. I'll return post with the specific info from my 91 FSM ltr today, unless someone else chimes in first.

Display CCM Data (Mode 1.2):
01 - Fuel Level (Gallons, tenths)
02 - Dimming Potentiometer
03 - Ambient Light Sensor
04 - Rear Defogger Timer
05 - Vehicle Speed
06 - Pass-Key
07 - Ignition Voltage
08 - Switched Voltage
09 - Cluster dimming
10 - LCD backlight dimming
11 - Radio & Climate dimming
12 - LED dimming
13 & 14 - Vehicle configuration
15 - Oil monitor count
16 - CCM version

Display CCM input status (Mode 1.3):

1 - PassKey fuel
2 - English/metric status
3 - Door key switch
4 - Right Door ajar
5 - Left door ajar
6 - key in ignition but in "off" or "acc" position
7 - hatch ajar
8 - Power door unlock
9 - Power door lock
10 - Parking lights
11 - Rear defogger input (car must be running)
12 - Seat belt switch
13 - High beam switch
14 - Low oil level switch

These values are either "1" or "0," and when toggled, the new value will be appended on to the old value (01 means it was 0 but is now 1).

Cycle CCM Outputs (Mode 1.4):

Selecting these options will manually activate the lights and sounds the CCM produces.

1 - Change oil light
2 - Check gauges indicator
3 - Fasten seatbelt indicator
4 - Security lamp
5 - High beam indicator
6 & 7 - chimes
8 - LCD blanking
9 - Defogger relay
10 - Courtesy lamp
11 - Low oil lamp
12 - Theft relay
13 - DAB relay
14 - door ajar light
15 - Horns (This will actually beep the horns, watch out!)

http://forums.corvetteforum.com/c4-t...n-96-cars.html

BTW, your VATS key is Key number 15 should you ever need to have a replacement key made, or should you lose yours.
1.2 01 17.6
02 0
03 162
04 0
05 0
06 211
07 12.7
08 12.1
09 69
10 69
11 69
12 74
13 107

Another note..Jumping A-G, and going to 1.2-6 gives you the value of the resistance of the current key in the ignition, not the VATS key needed to start your car. At first I thought this was an easy way around for those who lose there only ignition key..but not. Your CCM will "read" any key pellet you put in, just won't start unless it's the right one.
The number displayed ( yours is 211) correlates to a specific VATS key number which you match up in your FSM. Page 8D-59.
XXX Value = Key code number
33-38 #1
42-47 #2
52-58 #3
64-70 #4
76-83 #5
91-98 #6
106-113 #7
121-128 #8
136-143 #9
149-156 #10
164-170 #11
177-183 #12
188-194 #13
199-204 #14
208-213 #15 ( yours)
I'm just posting this for general refernce for others.

 

1.1 to 1.7 are diagnostic tests, not modules. 91s have two modules, the ECM and the CCM. When you ground pin G you are accessing the CCM which has access to the body and engine wiring plus the ECM. All the pertinent info is in the FSM section 8D.

BTW, what is wrong with your 91?

 

Great information from everyone, thanks for the info.

There have been a series of problems that ultimately lead to the car engine not even turning over.

First I had a problem when going over 30mph where I could only drive the car in other gears at higher speeds.
This problem just went away.

Second The car began to idle roughly when stopped and then the engine would stall, so I began to put the can into N when at a stoplight, I changed the spark plugs, and had an oil change.

Third the car began to make a very very loud constant pinging sound, but only when accelerating.

Lastly my car would start in a parking garage however I could only move it a foot before the engine would stall.

Now I'm trying to get it to a specialized shop that works on Corvettes however I would like to get a good idea on what parts I may need to prevent overpricing.

Prior to the car dying I brought it to 2 mechanics that had no clue as to what the problem was, so they suggested to order many parts and hopefully one would fix the problem.

Any suggestions will be taken into consideration. Thanks

 

Difficult to tell from your description since you give no hint regarding transmission type, but it almost sounds like the torque converter may not be unlocking if it is automatic.

 

I noticed a gap in the Corvette Induction Power Coupler casing, could this be the primary cause of all this trouble?


It has an automatic transmission however, would the torque converter cause the engine to stall, and if so what would be the cause?

 

If by power coupling you mean the air intake to the throttle body the answer is no, your 91 has speed density fuel injection so unlike a MAF system an air leak ahead of the throttle body would not affect engine operation aside from admitting unfiltered air.
The lock up clutch in the torque converter should only "lock" at highway speed to improve fuel economy and transmission cooling, if it remains locked at lower speed it can cause stalling or other driveability issues.
After reading your post again however I do not feel that is the problem, you say the engine will not turn over, the converter should not prevent the engine from cranking. If I misunderstood your post and the engine will start in park or neutral but immediately dies when placed in gear then the converter is a possibility, good luck.

 

Back to basics - do you ever get a service engine light? If not, does the service engine light even work? If this vehicle was an historical trouble maker, the previous owner may have just removed the bulb from the DIC. Anyway, look for stored error codes in the ECM - the procedure is in Section 8D page 9.

 

Are you still a member of this forum I would love to get a few answers of codes and where to find them in my FSM. I have the electronic version unlocked great manual but tough to find things in.