I have a 1991 G10 Chevy Van that came with an ARPB 7505 chip. Originally it had a 305 engine, but it was swapped out to a 350. I was told it should have an ASDU chip.

I was looking at the compartment with the chip in it and I noticed another smaller chip. Some sellers of used chips on eBay sell the second chip as well. All the auto parts stores sell just the big chip.

Should I be concerned about the second chip? Can you tell me what it does?

 

It is a calpack. Limp home chip. I believe it needs to be a V8. I dont think CID is an issue.

 

Thanks.

Some stuff I found from other sites:

The CAL-PAK (calibration package) is used to tell the computer how many cylinders the engine has and is also used for back-up fuel delivery should the EPROM fail. Apparently they are the same from vehicle to vehicle.

It is not used for a sensor failure, as the main chip has backup and limp routines in case of sensor failures.

The CAL-PAK also contaings 'limp-home' data in case the PROM fails.