92Q Seems to be Dead - Will not turn

[thirdq]

OK, this is the second time my Q45/92Q is acting up like this.

We drove some 90 miles yesterday (roundtrip), came back home no problems. Tried starting the car tonight and the motor will not turn. The lights and chimes are also fading away - seems the sign of less battery voltage.

Interestingly, this has happened once before, the car sat for 7 days while I was trying to find out how to replace the alternator - but then one day it started and has been running for the last 80 days or so w/o problem.

Last time when it happened, I gave it a jump from another car, it did start up but the electrical system seemed to be cutting in and out - the engine was shaky, the electrical instrument panel was coming and going out (while the car was running after the jump) and it was to a point that I did not feel comfortable driving the car to the mechanic. I stopped it, let it sit for 7 days, tried it and it came back like nothing happened and continued working for the next 80 days.

It happened again tonight - no power, no turning, no starting.

If it is alternator, why would this come back from the first failure and continue to run w/o a hitch for the last 80 or so days? the car is 126K, the alternator may be going out, I just wanted to confirm if indeed that is the problem.

The battery is kind of 6-8 months old.

Thanks
Modified by thirdq at 8:25 PM 2/19/2006

[maxnix]

Without measurements, sounds like you have been running off your battery power. Alternator sounds like it has passed its useful life.
Modified by maxnix at 9:06 AM 2/25/2006

[PopPop]

Without measurements, sounds like you hae been running off your battery power. Alternator sounds like it has passed its useful life.

If you can get it running again you can disconnect negative terminal from battery while car is running at your own risk! If the alternator is bad then the motor will shut down because battery carries load if alternator is bad! I said at your own risk because disconnecting battery terminals is not recommended because if there's a problem some where else in your electrical system it can damage ECU! I've never had that problem but thought I let you know! If you can't test alternator and battery your self. Take it to an auto parts store to be tested for free!

[thirdq]

SAMS club replaced the battery under warranty - the alternator checked out around 13.7v or so. So for now all is good.

thanks

[Q45tech]

The voltage alone is not a reliable test. You must look at/measure the alternator ripple voltage and the ripple frequency vs rpm, since it is a 3 phase AC to DC system.............3 separate windings feeding 3 separate diodes combined together [each winding provides 1/3 of total current].