Need help on my 87.
04-16-2014, 08:22 PM
#21
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I've looked really close at the memcal's for 10 + years and have never seen any significant difference that would indicate a rear end ratio requirement. In fact, some BCC's are identical with different codes. I believe this to be a myth due to GM showing some (not all) ratio's.
I suspect your multiple codes to be scanner related. Try the old memcal and see if you obtain the same result? Then try a different scanner.
I suspect your multiple codes to be scanner related. Try the old memcal and see if you obtain the same result? Then try a different scanner.
04-16-2014, 08:31 PM
#22
Drifting
More important is this is off the topic of the thread. Try the different memcals to eliminate its possibility, and then a different scanner.
04-17-2014, 01:21 AM
#23
Race Director
The ECM uses the rear axle ratio to calculate the vehicle speed in MPH. It's used EVERYWHERE, so it might be important...
For auto transmissions, the ECM controls the torque converter lockup. It also turns on the SHIFT light if you drive "too fast" (on my car that's 40 MPH) in Drive to remind you to shift to OD.
The ECM also controls the SHIFT light on manual trans cars. I don't know the details of what else might be involved since I have an auto and I haven't looked at the manual trans code.
For auto transmissions, the ECM controls the torque converter lockup. It also turns on the SHIFT light if you drive "too fast" (on my car that's 40 MPH) in Drive to remind you to shift to OD.
The ECM also controls the SHIFT light on manual trans cars. I don't know the details of what else might be involved since I have an auto and I haven't looked at the manual trans code.
04-17-2014, 07:55 AM
#24
Drifting
Some BCC's were used for multiple rear gear ratio's as seen here:
http://www.chevythunder.com/prom_bcc_1986.htm
Last edited by MrWillys; 04-17-2014 at 08:29 AM.
