Non-operational Tach

[84Q]

Well, the tach doesn't work on my 84 Quantum. I don't much about the system except that the tach is driven by the "W" terminal on my alternator(although I'm not sure exactly where the terminal is on my alternator). From what I've gathered, this is a fairly common problem. Any help would be really appreciated. Thanks in advance,
Aaron

[55mpg06]

1. I don't know too much about Quantum's but if it is like my MKII Jetta on the Bosch ones there will be two thin guage wires comming out of the alternator. If I remember right, one will be your alternator warning light (probably very near the power feed), and the other should be the Tach wire most of the time farthest away from the main power feed. The connections very, though so best to check both connections.

2. If the other gauges are acting strange (not inc speedo) slight chance it could be the voltage reg. on the back of insterment cluster (don't know if it applies for yours.)

3. With mine I found it to be the regulator in the alernator itself since I was about to replace the gauge itself when after putting in a new alt. for another problem I then had a tach. For mine, when it was on its way out I found that the tach worked for a while (especialy while cold) and then died. It progressivly got worse and worse until not working at all.

Hope this helps, sorry I am not as knowlagable as the other guys though..

P.S. spend the extra 30s and disconnect the battery first. Might get a little surprise otherwise and they HURT! :shock:

[burn_your_money]

Yeah have a look at the alternator. The W is usually stamped right into the casting. I find that it is usually caused by a poor connection at the alternator.