So where does low voltage affect YOU first?
Thread Starter
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
So where does low voltage affect YOU first?
Just curious because I know you can have identically designed electrical systems that exhibit entirely different symptoms when their power supply is compromised.
My car started throwing an SDM 1040 code for the past week or so(lost comms to EBCM), but everytime I looked it was showing as a history code. I tinkered with it a bit this weekend cleaning the 2 grounds on either side of the block. Then I get back in and just turn the key [ON] but I don't start it, aaaannndd now I've completely lost comms to the TCS as well. Great, I made it worse.
So I crank her up to pull into the garage, and the second the engine (alternator) spins up, *click* the TCS idiot light goes off, and the SDM code goes to history. Oh ok, my battery is dieing. I get it. 
So to the parts store I go ... new battery ... car is happy again.
But now I know. That SDM 1040 code is my forward warning for a weak battery. What's yours?
My car started throwing an SDM 1040 code for the past week or so(lost comms to EBCM), but everytime I looked it was showing as a history code. I tinkered with it a bit this weekend cleaning the 2 grounds on either side of the block. Then I get back in and just turn the key [ON] but I don't start it, aaaannndd now I've completely lost comms to the TCS as well. Great, I made it worse.
So I crank her up to pull into the garage, and the second the engine (alternator) spins up, *click* the TCS idiot light goes off, and the SDM code goes to history. Oh ok, my battery is dieing. I get it. So to the parts store I go ... new battery ... car is happy again.
But now I know. That SDM 1040 code is my forward warning for a weak battery. What's yours?
Le Mans Master
Joined: Feb 2002
Posts: 6,937
Likes: 21
From: Waldorf MD
When my battery was going bad, I would loose the settings on my DIC. If I had it set on Oil Temp when I turned it off, it would default to the odometer when I turned it back on. It would also loose some memory, like AVERAGE MPG.
If the battery gets down to 8.5 volts or lower while cranking (weak battery), strange things can happen.
These C5's eat batteries, especially if you leave them sit. I use an Optima Red Top AGM Battery (because the battery is over the computer) and I use a battery tender any time it sits for 3 days or more. AGM batteries are less tolerant of sitting idle.
If the battery gets down to 8.5 volts or lower while cranking (weak battery), strange things can happen.
These C5's eat batteries, especially if you leave them sit. I use an Optima Red Top AGM Battery (because the battery is over the computer) and I use a battery tender any time it sits for 3 days or more. AGM batteries are less tolerant of sitting idle.
Last edited by Oldvetter; Mar 1, 2010 at 06:11 PM.
