Tach Bounce/Power Window switches
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From: Dallas
Tach Bounce/Power Window switches
Couple of days ago noticed the tach needle bouncing wildly periodically...
Today when i depressed the power window switch to insure my window was closed the tach needle spiked to two or three thousand each time the switch was depressed with the window closed. The tach would spike when either right or left window switch was depressed. Have never worked on either door switches or tach. Am original owner....Where should i look to find the short? Any tips appreciated. Thanks in advance.
1980 L82
Auto
Today when i depressed the power window switch to insure my window was closed the tach needle spiked to two or three thousand each time the switch was depressed with the window closed. The tach would spike when either right or left window switch was depressed. Have never worked on either door switches or tach. Am original owner....Where should i look to find the short? Any tips appreciated. Thanks in advance.
1980 L82
Auto
Former Vendor
Joined: Aug 2006
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From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Something is spiking for sure. The two circuits are not related.
I'd maybe start with the tach filter and by-pass it... see if the tach issue goes away. But the power window issue causing the tach to increase is odd for sure. On the 1980 the tach goes though a pcb on the back of the speedo tach housing. It's common for the fingers on the printed circuit board to de-laminate and touch another finger or not touch at all... But I don't think this would be your issue either.
Since the power window circuit picks up it's ground from the motor being bolted in place, so I really don't know where to guide aside from the pcb in the dash. It's easy to go in there and look... you just need to remove the housing. 1978-1982 Corvette Speedometer And Tach Housing Removal Instructions
I'd maybe start with the tach filter and by-pass it... see if the tach issue goes away. But the power window issue causing the tach to increase is odd for sure. On the 1980 the tach goes though a pcb on the back of the speedo tach housing. It's common for the fingers on the printed circuit board to de-laminate and touch another finger or not touch at all... But I don't think this would be your issue either.
Since the power window circuit picks up it's ground from the motor being bolted in place, so I really don't know where to guide aside from the pcb in the dash. It's easy to go in there and look... you just need to remove the housing. 1978-1982 Corvette Speedometer And Tach Housing Removal Instructions
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