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connecting a Tachometer 04 3500
connecting a Tachometer 04 3500
I'm wanting to connect a VDO tach. the 3500 doesn't have a coil +/- so I assume I need to connect to alternator but where? besides the charge post there's 2 wires on a 4 pin plug out of alt. thanks https://cimg3.ibsrv.net/gimg/www.per...52caf24463.jpg https://cimg7.ibsrv.net/gimg/www.per...46687fcacc.jpg |
Your trying to connect a tachometer to the alternator?
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I believe he is just trying to power it via the alt.
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Originally Posted by RDF1
(Post 5519110)
Your trying to connect a tachometer to the alternator?
Originally Posted by shakenfake
(Post 5519125)
I believe he is just trying to power it via the alt.
thanks |
Originally Posted by thebrain
(Post 5519128)
yes per instructions VDO provides. thanks
no power (switched 12vdc) is pin #2 pin#3 ground pin#4 is sender (not sure where to connect pin#4 thanks They mention a "red harness." I think they may talking about the red/blue connectors at the ECU. You may have that, and not the blue/green ECU. |
Since you only have a 1 wire alternator and no/multiple coils, and no distributer, the Crankshaft/Camshaft position sensors provide engine speed to the ECU. You will need to tap the ECM connection to get the signal to the Tach. I don't know which wire will provide the signal but there may also be an issue since the ECM may not be a 12V signal. I do know the only way to get the info in your engine is from the ECM. There is a possibility the Tach you purchased is not compatible with your truck because the Tach schematic is for older engine configurations, Coil schematic or 4 wire Alternator, which haven't been used after GM went to the ECM, fuel injection, and crank/cam sensors. (the coil or "electronic control box (mopar) is pre-ECM. Maybe some else on the forum has the ECM pin for a Tach trigger, sorry but I got rid of my Helm 2000 Silverado manuals a couple years ago.
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Originally Posted by strutaeng
(Post 5519135)
You may want to read here: https://ls1tech.com/forums/generatio...ch-signal.html
They mention a "red harness." I think they may talking about the red/blue connectors at the ECU. You may have that, and not the blue/green ECU. I can set the # of cylinders on tach got lost when they wanted to boost the tach or maybe that is just for autometer tachs.thanks though.
Originally Posted by OTCyber Guy
(Post 5519307)
Since you only have a 1 wire alternator and no/multiple coils, and no distributer, the Crankshaft/Camshaft position sensors provide engine speed to the ECU. You will need to tap the ECM connection to get the signal to the Tach. I don't know which wire will provide the signal but there may also be an issue since the ECM may not be a 12V signal. I do know the only way to get the info in your engine is from the ECM. There is a possibility the Tach you purchased is not compatible with your truck because the Tach schematic is for older engine configurations, Coil schematic or 4 wire Alternator, which haven't been used after GM went to the ECM, fuel injection, and crank/cam sensors. (the coil or "electronic control box (mopar) is pre-ECM. Maybe some else on the forum has the ECM pin for a Tach trigger, sorry but I got rid of my Helm 2000 Silverado manuals a couple years ago.
my alternator on the 04 express has 2 wires on a 4 wire plug solid white an solid orange. this in addition to the larger charge post that goe's to battery. what is the 2 wired piece to left of alt. ontop of firewall? could this be an external regulator for the alt.? edit:if I had a newer Tach. designed for the coil to plug type vehicle would I still have to cut into the main wire harness? image of alt. thanks for tach advice https://cimg3.ibsrv.net/gimg/www.per...080e1203f4.jpg https://cimg9.ibsrv.net/gimg/www.per...e3314da42a.jpg |
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