Purple87SS
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- Mar 16, 2005
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What would possible cause the stock digital tach in an 87 WE4 to always show it redlined???
Thanks in advance!
Thanks in advance!
Stock Tach
- Thread starter Purple87SS
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- Aug 1, 2003
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check the connectors behind the alternator , they should be hanging out of the main harness and taped to it
one is for the tach output for testing or for aftermarket tach
the other is the fuel pump prime lead which when connected to 12v will run the fuel pump which is usefull for draining the tank through the fuel rail fitting ,
normally there is nothing connected to them but if these are connected to each other than the tach will redline
or it could be bad and need service as most are inaccurate from age , john casper services them (casperelectronics.com)
one is for the tach output for testing or for aftermarket tach
the other is the fuel pump prime lead which when connected to 12v will run the fuel pump which is usefull for draining the tank through the fuel rail fitting ,
normally there is nothing connected to them but if these are connected to each other than the tach will redline
or it could be bad and need service as most are inaccurate from age , john casper services them (casperelectronics.com)
83ttypecooled
Active Member
- Joined
- Sep 14, 2003
- Messages
- 2,082
Tach troubles
Hi,
I have what I suspect is a common problem with my car, tach reads exactly double the actual rpm. I think your trouble is very similar. I checked output at the white wire test connector, tach signal,used the duty cycle setting on my Fluke meter, and divided the output in half. The result agreed with my inductive tach's information.Maybe that genius, Casper, can help. I am sure my problem is in the instrument cluster itself. Good luck!
Hi,
I have what I suspect is a common problem with my car, tach reads exactly double the actual rpm. I think your trouble is very similar. I checked output at the white wire test connector, tach signal,used the duty cycle setting on my Fluke meter, and divided the output in half. The result agreed with my inductive tach's information.Maybe that genius, Casper, can help. I am sure my problem is in the instrument cluster itself. Good luck!
