Just yesterday had the following occur:
1. Noticed that the tach needle would bounce a bit towards zero. Like it lost signal for a msec, then back for a few seconds, then lost signal again. Did this for about five minutes and then all was fine. Of course it has turned a bit cold here, and this is the first winter for the car here in Tucson.
2. On way home from work yesterday, noticed idle had become a bit rough at stop lights; and finally the Check Engine Lite came on. I cycled through the Gauges and noticed Battery Voltage was at 13.7....13.6....13.8......when normally it is at 14.1 or 14.2. Got home, pulled code; P0101 - MAF. Pulled MAF off, looked clean, checked hoses and everything...all seem fine. Cleared code.
3. Went for test drive this morning. Battery voltage at 14.1 or 14.2. Idle was fine, drove fine for a few minutes and then the tach needle bounced a few times and then stayed at zero. Went to Battery Voltage and again it was 13.7..13.6....13.8...etc. Tapped the top of the dash above tach a few times and tack springs back to life. Further tapping on dash did nothing...tack worked fine...Battery Voltage still lower than normal. No Check Engine Lite came on, but idle seemed a bit rough....but not sure.
Got home and put my DMM across battery terminals and had 14.1 / 14.2 whereas display continued to show 13.7...13.8..etc. DMM was pretty steady at 14.1 / 14.2.

So I am trying to put all of this together. Battery is only three months old, cables are clean and tight. Have checked under battery and no damage to wiring from battery leaking.

I bought the car out of Florida last Feb and all has been fine....other than finding sand in lots of places...topic for a different thread.....

I have cleaned one of the frame ground connections last summer, but only the one. I also had the instrument cluster out when I first got the car in order to fix the HUD.

Appreciate any comments or thoughts on this......

Thanks

 

Crap....fixed my typo...yes P0101 is correct.

I will check the fuses/voltages per above.

I did check the MAF wires and connectors/contacts when I had it off; all seem to be fine. The MAF is at the factory location as is the wiring harness.

Regarding the MAF diagnostics, I was just going to probe the connector with engine running to ensure that voltage, ground is there and output signal is changing. If that shows to be questionable, then I will request the shop manual pages from you; do not want you to go through the effort unless necessary....THANKS in advance.

 

Okay here are the numbers with engine running:
Across battery terminals: 14.46Vdc
Under hood fuses: #18, #19, #22 @ 14.45Vdc, #16 & #13 @ 14.21Vdc
IP fuses: #19 14.2Vdc, #21 14.3Vdc, I do not have a #22 fuse, but it showed 14.3Vdc.

I had the battery voltage on the display when I did this, just after starting engine voltage showed 14.1Vdc. After making the above measurements, battery voltage was varying between 13.7 to 13.9Vdc.

Reving engine changed voltage 0.1 - 0.2 Vdc.

Opinions, comments....

 

Voltage on analog dash gauge was steady, it was the digital display that was varying....and is the varying voltage reading a concern? Something is not quite right as the digital battery voltage had always been a steady reading in the past and now it is not. Do not know if I should pull the instrument panel out to re-seat the connector...which might be the "fix" for the tach problem...or to continue to clean frame ground connections....of which I have not found any dirty ones yet.

 

Went for a test drive for a good 30 minutes...no CEL and running normally...???
Voltage on digital display still varied, but then have to say that I usually do not drive around with the battery voltage on the display, usually coolant temp, so perhaps all is fine once again.....time will tell.