84 K20. 350 with 700R4. This switch is mounted to the firewall near the brake booster. Has both vacuum and electric running to it. Anyone have a clue what it is?
CK5
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File this under WTF is this???
- Thread starter TommyD11730
- Start date
Might be they put it there anyway,in case it came with a TH350C transmission--or perhaps they use it for another purpose other than controlling the torque converter lock up...?...
Yep. That's how GM handled converter lockup without a computer. I'm guessing that is what was used to determine the load on the engine in order to electronically engage/disengage the converter. From my '83, I felt it was a pretty good system. Mine never gave me any problems.
Thanks Guys. I followed the vacuum diagram and it sounds like basically your correct. Works off ported vacuum so I guess it's a poor man's TPS 
My '81 G-10 van with a TH350C transmission has that same vacuum switch...never had issues with it,though when I first got the van I discovered the converter wasn't locking up ,due to the stoplight switch being out of adjustment...one night I noticed the brake lights were "stuck on"..
I had noticed the transmission seemed to be running "hot" on a long trip (150 miles) I made,and when I listened for the RPMs to drop when I stepped on the brakes and it didn't,I realized the stoplight switch is tied into the lockup circut--once I adjusted the pedal switch the converted locked up normally again...probably would have cooked it eventually if I had not discovered that !..
I have seen similar setups on other cars used to shut off the A/C compressor on wide open throttle too..gives you a few HP back when its most needed..
I had noticed the transmission seemed to be running "hot" on a long trip (150 miles) I made,and when I listened for the RPMs to drop when I stepped on the brakes and it didn't,I realized the stoplight switch is tied into the lockup circut--once I adjusted the pedal switch the converted locked up normally again...probably would have cooked it eventually if I had not discovered that !..
I have seen similar setups on other cars used to shut off the A/C compressor on wide open throttle too..gives you a few HP back when its most needed..
