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I was adjusting the carb on my '71 LT-1 this weekend when the TCS engaged. The car was warm and of course in neutral. Now it will not disengage. The only way I get it to stop is by unplugging the electrical connection. Any suggestions on how to diagnosis where the problem lies. The only thing I cam think of is the TCS temp switch is bad. Is this a common failure and if so is there a way to test it? Any other common problems that cause this situation?
The system is techincally called CEC (combined emission control) on a '71 differentiating it from the TCS system used in '70 and then again in '72 and later. A pair of 'smart' relays mounted on the firewall forward of the driver, control the CEC relay.
There are several conditions that cause the control relays to 'fire' the solenoid and the system is described in your copy of the Chassis Service Manual, Emissions System. But, they are:
(1) Engine has just been started and the 15-second timer hasn't expired.
(2) Engine is running but is not yet up to normal operating temperature.
(3) Engine is running and coolant temp has risen ABOVE normal operating temp.
(4) Engine is running and transmission is in high gear.
Unfortunately, due to the late breaking inclusion of the CEC system for 1971, there is NO troubleshooting proceedure in the CSM and the engine wiring diagrams for ALL 1971 Chevrolet vehicles are WRONG. This was addressed by a dealer service bulletin that few have.
I wrote a technical article on this for NCRS Restorer magazine as part of my Founders Award prerequisite (describes the above and supplies correct engine compartment wiring diagram + trouble shooting table). But, it appears the article was so narrowly focused (only deals with 1971 Corvette) that it never went to press.
I would be interested in your article and troubleshooting guide as well. One of my '71 LS6's is missing the CEC and wiring portion. I recently acquired a NOS CEC unit and a NOS wire harness. I could certainly use your knowledge in this area as well.
Jack if you resubmitted the article you wrote do you think it might get printed now? I bought a 71 service manual for my 70 Corvette when I bought it new because the 70 service manual I ordered was for 70 Chevrolets except it said 69 Corvette on it and I later got the 70 Corvette supplement when I found out that Helm had one for the 70 service manual. Now I find out that the engine wiring diagrams in my 71 service manual are wrong.
personally (off-board via email) and agreed to terms and conditions have received a copy via email. Since the article's status is submitted, accepted and un-published, it has NOT been copyrighted by NCRS. Therefore, I can NOT place the article in 'public domain' to protect the NCRS intellectual property rights position. So, you must agree to use copy's sent you for your own personal use and NOT to distribute or to make public the information.
Posting additional "I'd like a copy" requests here won't get you response(s). Click on one of my posts in this thread and send me an email...
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