ccm question
09-23-2018, 10:13 AM
#2
If you're using a 'USED" CCM it would have to have the same VATS reference embedded in the programming. It would be a coincidence. Also if using a 'USED' the mileage displayed on the dash would be the mileage from the 'donor' car and if scanned it would also display the VIN of the 'donor'.
You didn't mention REMAN or USED so you might start with mentioning what you've bought or anticipate buying. Learning VATS to a REMAN requires all of the current keys that you have, programming miles and entering the VIN.
You didn't mention REMAN or USED so you might start with mentioning what you've bought or anticipate buying. Learning VATS to a REMAN requires all of the current keys that you have, programming miles and entering the VIN.
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polo91 (09-23-2018)
09-23-2018, 01:20 PM
#4
09-23-2018, 02:52 PM
#5
Drifting
Thread Starter
If you're using a 'USED" CCM it would have to have the same VATS reference embedded in the programming. It would be a coincidence. Also if using a 'USED' the mileage displayed on the dash would be the mileage from the 'donor' car and if scanned it would also display the VIN of the 'donor'.
You didn't mention REMAN or USED so you might start with mentioning what you've bought or anticipate buying. Learning VATS to a REMAN requires all of the current keys that you have, programming miles and entering the VIN.
You didn't mention REMAN or USED so you might start with mentioning what you've bought or anticipate buying. Learning VATS to a REMAN requires all of the current keys that you have, programming miles and entering the VIN.
Last edited by polo91; 09-23-2018 at 02:55 PM.
09-23-2018, 03:27 PM
#6
I had planned on buying a used one, but it sounds more complicated than what I thought. The reason for the replacement was that the fuel gage doesn't work. I ran the diagnostics as the shop manual chart shows and the result is "replace CCM". I think I will just keep filling it up every 250 miles and check on getting my CCM rebuilt.
09-25-2018, 11:09 AM
#9
Have you ran a bottle of Techron thru the gas tank? I’ve had fuel sending unit inaccuracies and after running thru a full tank of gas w/ a bottle of Techron it worked normal.
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polo91 (09-30-2018)
09-25-2018, 11:09 AM
#10
Team Owner
Pro Mechanic
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polo91 (09-30-2018)
09-30-2018, 08:42 PM
#12
Drifting
Thread Starter
Sometimes you have to be smarter than the Shop Manual. The diagnostics does not mention the float, but all was well when I replaced the fuel pump a couple of years ago. I pulled the sending/pump unit a few minutes ago and found the scraper wire was not touching the resistor. That has been corrected and all is well. Thanks guys you saved me about $300 and the disappointment when the CCM would not have fixed the problem. This forum has been a big help for me for the last ten years.
09-30-2018, 10:03 PM
#13
Team Owner
Pro Mechanic
10-01-2018, 09:23 AM
#14
It certainly seems 'odd' the FSM is assuming that the fuel sender is operating. A meter and checking the 'PURPLE' wire for continuity & also value I believe should be a 1st check. A later year which of course is a bit more sophisticated actually hints the first check is 'sender' & IP comparisons.
10-01-2018, 07:00 PM
#15
Drifting
Thread Starter
I read the troubleshooting flow chart for "gauge reads empty" again. My 91 book, page 8A-82-15 Chart #12.
First step is disconnect fuel tank unit: Does gauge now read Full? Yes = Replace fuel tank sending unit. (This is CLASSIC behavior for the old analog system. Open circuit = FULL).
No= Connect test light between connector terminal and ground.
Is test light "ON"? Yes = "Replace CCM". (There isn't enough current at 5V from the CCM to light a 12V test light. (again, this is for an analog system that operates at 12volts).
No= Check for short to ground. (This is the only correct branch of the chart. A grounded purple wire will indicate FULL).
So they check the sender in the first step, and if the state of the gauge changes they say change the sender. But the inference open circuit = FULL, is NOT correct for the 1991 Corvette.
This chart is DEFINATELY written for the old analog dual-coil gauge. Not the 5V CCM system.
First step is disconnect fuel tank unit: Does gauge now read Full? Yes = Replace fuel tank sending unit. (This is CLASSIC behavior for the old analog system. Open circuit = FULL).
No= Connect test light between connector terminal and ground.
Is test light "ON"? Yes = "Replace CCM". (There isn't enough current at 5V from the CCM to light a 12V test light. (again, this is for an analog system that operates at 12volts).
No= Check for short to ground. (This is the only correct branch of the chart. A grounded purple wire will indicate FULL).
So they check the sender in the first step, and if the state of the gauge changes they say change the sender. But the inference open circuit = FULL, is NOT correct for the 1991 Corvette.
This chart is DEFINATELY written for the old analog dual-coil gauge. Not the 5V CCM system.