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914World.com _ 914World Garage _ Tach signal - not making it to dash....

Posted by: Aaron Cox Jun 9 2006, 09:38 PM

allrighty...

tach worked fantastic before paint.... now everything is reassembled and the tach doesnt work....

mallory CDI box with modded tach (see CDI tach mod) worked flawlessly, and a late gauge would work fine too...

now, early modded tach doesnt work, nor does a late model tach.

i checked gauge connections, and i checked engine bay connection.

the blk/purp wire connects to tach output of CDI box, and is plugged in at gauge...

where should i be looking??? no signal is making it to the tach...

Posted by: DNHunt Jun 9 2006, 09:53 PM

Get a volt meter and check continuity of the black purple wire from the coil end to the gauge end (broken conductor). Then check the black purple wire for continuity to ground (short to ground). Check fuse S-9 (74). Check the red and white wire from the fuse to the gauge for continuity and short to ground if blown.

Dave

Posted by: Dave_Darling Jun 9 2006, 09:54 PM

Follow the wire. It goes to the relay board, then through the board into the main wiring harness. From there it goes to the tach.

Check to make sure the T-12 and T-14 plugs are plugged in correctly and fully seated on the relay board. Make sure the black/purple wire is in the right spots in both connectors. Make sure the connections on the relay board are OK, and that there is connectivity from the one pin to the other....

--DD

Posted by: Aaron Cox Jun 9 2006, 10:19 PM

i believe the signal out of the box is a 12v square wave... (what i think i read....)

ill check fuses... and retrace wires....

ill put an oscilliscope on it tommorow if i have time before work....

little things holdin me down LOL

Posted by: Dr Evil Jun 9 2006, 10:42 PM

Dude, you dont need an O scope, just disconnect the wire ends and see if you have continuity to each other and ground. If to ground, you have a prob