Question for Joe Lucia

[Robert E.]

Joe, I was wondering if you could confirm the application of GM #3990842 as listed on ebay #7973564712 as a '71 TCS Transmission Relay. I have a 4 speed car and the listed relay doesn't resemble the one on my car.

Thanks

Robert

[Jack H.]

Re: Question for Joe Lucia

1971 cars didn't have 'TCS' to be technical about the issue. This was a 1-year only instance of the use of 'CEC' (Combined Emission Control). There were two paired/mated relays associated with the application:

3990842, Reversing Relay
3990843, Delay Relay

The reversing relay is still available from Chevy, although the package details differ from factory orignal relays used in 1971 production. The delay relay has long been discontinued...

Originally, when these cars were built there was a prime supplier for both relays (Littlefuse) and a second source for each relay (UCC was the reversing relay alternate source Fasco supplied the alternate delay relay assu). The prime and secondary supplier parts were mixed on the assy line and you'll sometimes see the alternate supplier's relay in place of the more common Littlefuse relay on various cars rather randomly.

The original relays (from all three sources) were embossed with the GM P/N and they were date coded. Few, know how/where to read the date codes to verify factory authenticity of the control relay(s) vs. those installed from service replacement sources that weren't physically date coded, but some of the more senior judges with '71 expertise DO know how/where to read/verify...