trouble code?

[gbluett]

I have a stock 91 coupe, L98 automatic, in the center of the guage cluster next to the digital speedometer is a display for the mileage range. The problem I am having is that the display will alternate between the mileage range and SYS will flash, this will continue the whole time the vehicle is in use. I never herd of this before and cant find anyone who has seen this. Anyone know what this is? any help would be great Thanks

[ynkedad]

No idea...Anyone????

[navy2kcoupe]

When gmjunkie sees the post, he WILL have something to say!
Andy

[gmjunkie]

Well with out seeing any actual codes,
1. I'd start by checking for Codes!! (I'm sure there is some stored!)
2.I'd Check All Engine and Chassis Grounds!!
3.I'd Check the battery for Voltage and Load Test!!
4.I'd check the Connection on the Big Red wire on the alternator!!(Not so much the nut on the alternator,but the eye to the wire!!I've had several that I had to replace the eye because the connection between the eyelet and the wire was green inside the crimp and getting a bad connection!!) I made a 1200 mile + Round Trip service call because of this wire on a car I sold to a Buddy in Jensen Beach!
5.I'd Check the Alternator for Charging DC Voltage, and AC Voltage slipping past the diodes in the Alternator!! (Any more than about 2-2 1/2 Volts AC or a bad connection at the alternator will make the Digital Dash act up!!

[MRS. XTREME]

The path to the answer is found in the GM shop manual for a ’91 Corvette; Section 8D which covers the car’s Central Control Module. The CCM is similar to the C5/C6 Body Control Module. The two other computers in a ‘91 illuminate a light when they have detected a fault (“Check Engine” or “Service ABS”). The CCM displays “SYS” in the center of the digital display when it detects a fault, flashing at a rate of about once every five seconds.

To get the CCM to display a code for the fault it has found, connect the ALDL connector pin G to pin A. Turn on the ignition. The CCM will enter its diagnostic mode, displaying detected faults in the digital display. There are a total of 30 trouble codes. But 7 of those codes are related to the VATS system and those are not likely the cause of this problem since the car is operational. The numeric code will be preceded by either a C for current or H for history. (For example it may display C21 or H21; and may even display both C21 and H21 indicating there is both a current and historical fault.)

Tell me what code is displayed and I can give more hints.