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lost tach and cyl.

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help , i lost my tach and a cyl. , i cleaned the tci plugs and the plug down by the seat , nope not fixed installed another tci , nope , same thing . anybody know why the tach is not working ? when i 1st start it up the tach moves a little bit but a soon as it is running no tach , help


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Go to Service Manual on this web site:

See, page 7-1.


Signal to one cylinder and ( looks like #2 Cyl ) the Tack comes from the TCI output of #2 cyl.


The ( Gy ) gray wire out from the TCI 8 pin plug goes to the Coil Primary, and taps off the Tach. That the signal.


Possible, trouble,

1. the TCI output is bad.


2. the Gy wire from the TCI to the ( splice) where the wire is spliced into these Three Items. The Coil primary, The Tach, and the Fuel Pump control Relay.

Note: you will probably have to Pull the Air Filter Box to get access to the 8 pin plug on the TCI, to Take Continuity Checks.


3, inside the TCI there Might be a Bad Solder Joint where this pin from the 8 pin plug is Soldered to the Circuit board.


Things to check.


1. do Continuity check from Gy wire at the Tack, going to the pin with the Gy wire on the 8 pin plug of the TCI.


2. pull out the TCI, open cover, check solder conntct from that wire to the plug, Resolder the connection with 10 to 15 Watt Pen Soldering iron.


3. find the two wire pull apart plug going to Coil primary , open this plug and clean it.


4. When plug is OFF Coil Primary, Check the Resistance " Thru" the primary winding, it should be about 3 to 5 ohms.


5. Check to see if the Primary winding Is shorted to Ground Inside of the Coil. You might have a Bad Coil, which is shorting out the Signal from the TCI.


However, haveing said all this, I would say the most likley cause, is the Wire from the 8 pin plug ( the Gy wire) going to the " Splice " as shown on page 7-1.


If you find no bad connections, then I guess you would have to assume the TCI is bad.


You most likly have an open wire ( ie. no continuity ) OR, a Bad output signal from the TCI. ( most likely just bad solder joint to the circuit boare )


This should get you started.


Also, see page 8-41 Master Schematic in the Service Manual, for more detailed wireing then is shown on page 7-1.

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Is one cylander still out? THe tach problem could be either the solder connections on the pins of the connector for the cable on the dash. You also may have problems ith the connectors for the pickup coils...



You are correct here, if no signal from the Pick ups and the #2 cylinder is not being fired from the TCI, you would have not Tack signal.

Find the 5 wire "White " plug located, on left side just behind your left knee as you sit on the bike. Open and Clean this plug, Tug easy on all the wires, make sure they are still crimped into the pins, and plugs both sides of plug.


clean ALL plugs involved with CRC 2-26 Electrical contact cleaner.

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kwel !! i swapped out tci's and clean the 2 plugs , samething , i am going to hard wire the 5 pin white plug [ i cleaned it 3 times today with no luck , i am goin the look for the splice goin from the tci to # 2 coil . now i got to get the book out ,

thanks guys , wish me luck !


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Did you stick the OHM meter leads into each side of the 5 wire plug,

(( with the plug connected )) and measure the Actuall resistance thru the Plug. ?? If you have an ohm meter, do this before you start ripping and tearing anything else. The signals comeing thru this plug are VERY LOW VOLTAGE, ANY EXCESSIVE RESISTANCE HERE CAN BE BAD. You want to make sure you have "ZERO OHMS OF RESISTANCE " Thru these 5 pins. Don't assume anything here. Get an OHM meter.



ONE more possibility, Up behind the TACH, there is a plug with 4 wires in and out. Going to the TACH. I doubt this, is happening, but there might be a problem INSIDE of the TACH itself,

(( It has a small electronic circuit board in it , might have an internal short circuit ))


drawing down the Signal, thus the coil not fireing. This is way out in left field, but if it were so, Then just by disconnecting this plug, then the Coil should start fireing Normally.

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thanks , i have a few ohm meters but the 1 i have at home sucks , harber fright 3.85 . great for the basics , i did not know about the low sig. voltage going through that plug , i can now see why i mite a problem , on the 86 vr , do's it have 2 crank sencers ? i think i'll go find my book and see how this system works .

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