My tach would work sometimes and now not at all. I checked the connections at the back of the tach and the wiring harness on the engine, but could not find any shorts or bad connections. The other guages work. Any suggestions?
Does the tach ilumination come on when ignition is switched on? (best to check this at night). Does the alternator charge properly and are you using the stock alternator?
The tach is operated by the alternator. The W terminal at the back of the alternator sends the signal to the tach. Follow this fault finding list; -Check connections on rear of tacho, especially black/blue wire, terminal 4 -Check connection of black/blue wire on rear of 1st alternator (W connection, usually a bullet on flying lead, or lowest connection on alternators with 3 pin coupler) -Check continuity of black/blue wire from alternator to tacho -Measure voltage from alternator W connection to earth (ground), should be approx. 7.5 9.0 volts AC
I will check this all out on Saturday, Stanley. We have the standard alt.
I did have some electrical problems on Monday which might be related. My batt meter said I had 93% of capacity left in the house bank when we woke up. We motored for about an hour and when we got back to the dock, the house battery was very low and the radio, depth finder and refrig were off.
Is there a way that an issue with the alt. could have caused the battery to drain faster than normal?
You need to check your wiring very carefully. What voltage output are you getting from the alternator? Is there a drain on the system? Check for electrical loss because of a bilge pump stuck on or similar. If you are not sure of how the check the system properly, I suggest that you ask a marine electrician to help you.
Well, maybe everything is not fine afterall. Sometimes when I start the engine, the tach will work and sometimes it will not. Last night at the boat it worked on 2 out of 6 starts. I did not touch anything between attempts and all connections seem to be fine although access is limited behind the alt.
This is Farron, lets see if we can help you out here.
Provided the alternator is still charging and the tach is getting power, (the light should be on) it sounds like you have a connection issue. Probably with the signal wire from alternator to the tach.
The tach reads a signal from the alternator. The W terminal at the back of the alternator sends the signal to the tach. Normally this will be via the black/blue wire that runs from the back of the alternator through the harness to the back of the tachometer.
Check the connections at the alternator and harness plug and the tachometer. Especially the black/blue wire, at terminal #4 on the back of the tachometer and the plug at the back of the alternator. (W connection, usually a bullet or flying lead, or the lowest connection on alternators with the 3 pin plug)
Check continuity of black/blue wire from alternator to tachometer - Measure voltage from alternator W connection to ground, this should be approx. 7.5-9.0 volts AC. Perform this same check at the back of the tachometer at terminal 4 where this voltage should also be present.
These checks are pretty easy to make with a standard volt ohm meter.
If you are in doubt or do not have a meter, a competent mechanic/electrician can fault check a tach in a very little time.
You have verified the continuity and condition of the sender wire from the alternator to the tach.
The tach operates correctly when the alternator is operating but stops when the alternator stops charging.
All other connections and voltages check good.
I suspect that you may have a bad alternator.
Intermittent problems are the hardest to diagnose. I would suggest removing the alternator and have it spin checked at a good alternator/generator repair shop.
-- Edited by Farron Peffer on Tuesday 31st of August 2010 03:15:02 PM
