I'm about ready to start my car (waiting on a distributor) so today i threw the battery in it to see if it had any juice left, it didn't have enough to roll the windows down but it had enough to light up the cluster and one headlight. as soon as i put the key in the primed position the speedo went up to 20 mph. WTF i went and unplugged the connector from the VSS, check the gauges again, it still says i'm going 20 and now it says i have about 1/8th tank, there is no gas in the tank, there has not been for about 8 months. again WTF
any ideas?

 

My guess is that if you have such low voltage in the battery, it is too low to run anything electronic properly. Charge the battery and if they still read wrong, then be concerned. All electronic stuff has a threshold that it will not work at all below and often work oddly when near that lower limit.

 

check all your grounds

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mohudsolo &raquo;</TD></TR><TR><TD CLASS="quote">My guess is that if you have such low voltage in the battery, it is too low to run anything electronic properly. Charge the battery and if they still read wrong, then be concerned. All electronic stuff has a threshold that it will not work at all below and often work oddly when near that lower limit.</TD></TR></TABLE>

Usually that is the case, I've seen more than a few come in to the shop with a dead battery and the speedo and tach pinned at the extreme max, problem solved after putting in a new battery.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the DR. &raquo;</TD></TR><TR><TD CLASS="quote">

Usually that is the case, I've seen more than a few come in to the shop with a dead battery and the speedo and tach pinned at the extreme max, problem solved after putting in a new battery. </TD></TR></TABLE>

Yup, my dx's xluster went nuts when I had a nearly dead battery. Turn to ign my tach said 5k and I had a full tank but it read empty and I was already at operating temp, woop.

 

OK so last night i hooked up the VAFC and put jumper cables on the battery (that's a good solid 12 volts) turned the key and got the same 20mph and now it says i'm at half a tank, all the other gauges are fine and the vafc works fine. i know the dizzy i've got is dead but i cranked it just to see if it would, the gauges went dim and it just kinda went err....err really slowly, at the rate it waas cranking i'd say it would take about 30 seconds to fully turn over. keep in mind this is all still with the jumpers attached to a running car. so once again WTF

 

Remove and clean all the connections on the battery and starter and ground. That may or may not help. The battery in the car may be damaged internally and not allow a charge through it. I've found that when a battery has sat for a long time and maybe been frozen the internal connections can get damaged and they no longer let 12 volts through. Either get a new battery or take one out of a properly running car and try again.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by evilhatch2.0 &raquo;</TD></TR><TR><TD CLASS="quote">check all your grounds</TD></TR></TABLE>

That will cause your problems... Check all grounds, Thermostat ground ect.