| Re: 86 vette switching an auto trans to a manual transmission |
Subject: Re: 86 vette switching an auto trans to a manual transmission by CentralCoaster on 2009/7/27 18:21:13 GM changed the gear switches several times. I don't know what all 3 of those do. In 85, the dash switch, coolant temp, and 1st gear switch all fed into the computer. If the dash switch was on, Coolant temp was >140F, and 1st gear was off, Then the computer grounded out the underhood relay which sent 12V to the overdrive spade connector, and 12V to the dash indicator light. Fairly simple setup, but it requires a toggle switch for the overdrive. The one you have probably has a momentary switch. Also note that there was no reverse gear switch, the computer didn't care if the car was in reverse. For your sake, you need a latching relay that can also reverse position, in order to use your momentary switch to cause the relay to stay closed. I wouldn't worry about the gear switches. The overdrive won't activate in 1st gear anyways unless it's building up enough pressure to close it's internal lowpressure switch. And the coolant temperature input is just a nuisance in cold weather. If you want an overdrive indicator light though, it would go on anytime you hit the switch, even if the overdrive isn't on. Which is fine really, just power it off the same relay you use to power the overdrive. If you wanted to get fancy, you could run the relay signal through your 4th gear switche, so the overdrive only worked in 4th. Here, I guess it's called a "flip flop circuit". You can buy a little module that does all of that for you, some even have a small battery so they don't lose track of the state of your switch when you shut the car off. But you'd probably want it to default to off anyways. http://www.diyaudio.com/forums/showthread.php?threadid=123864 Don't expect to build it yourself out of relays, it would take 4 or 5 relays to do it. |
