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2008 Pilot Doesn’t start. Replaced Alternator and Battery. Worked for a week.

3K views 10 replies 7 participants last post by  plplplpl 
#1 ·
My 2008 Pilot SE AWD will not start. I replaced the battery and Alternator a week ago. Car ran fine. Now, nothing happens when I try to start it. What could this be?
 
#3 ·
Were you getting sluggish starts before replacing the battery and alternator? My wife’s Pilot was taking about a second longer than normal to crank. Initially replaced the battery which seemed to resolve things for a couple weeks, then the issue came back. Replacing the starter resolved it. If you have a voltmeter you can do some quick checks to make sure it’s not the starter relay prior to replacing the starter. My Pilot had 102k miles at 14 years when the starter was replaced. It’s about a two hour job first time around if you DIY.
 
#5 ·
Hold right there. If you were able to jump start, then it would be a battery issue.
Take a multimeter and measure the voltage across the battery posts. You should read 12V when the car is turned off and 14-14.5V when the engine is running.
If you install a new battery and it drains, then either your alternator is dead or you have a load which stays on when the car is turned off. Aftermarket alarms are notorious for the latter.
 
#6 ·
Since OP already replaced the battery and alternator last week I’m guessing there is a parasitic draw on the system. Easiest way to check is to put the multimeter into millivolts DC mode and measure voltages across the fuses. The Pilot needs to be off with no key in the ignition while measuring. Any fuse with a reading out of line with all other measurements points to a current draw on that circuit.

If OP was able to jump start the dead battery, and presumably drive the Pilot around the block, it seems the alternator and cabling & fuse between the alternator and battery positive are functioning. Voltage measurements across the battery, once the battery is charged, would verify this.

OP, you will likely need to charge the battery prior to measuring voltages across the fuses and verifying the charging system.
 
#10 ·
I have similar problem of battery and alternator are told working properly but intermittently, total drain on battery overnight. Replaced the AC compressor relay based on common problem feedback from a mechanic friend and seems to be same suggestion above. No luck in shot gunning or throwing parts at the problem.

I starting parasitic current draw tests but unfortunately, when I remove the battery connection for accurate current measurements, the problem goes away (meaning < 30 mA draw). Decided to start measuring voltage drop across fuses to determine what is pulling extra current and all signs are pointing to the ACG S fuse (intermittent).
 
#11 ·
I starting parasitic current draw tests but unfortunately, when I remove the battery connection for accurate current measurements, the problem goes away (meaning < 30 mA draw). Decided to start measuring voltage drop across fuses to determine what is pulling extra current and all signs are pointing to the ACG S fuse (intermittent).

So the no. 4 15A fuse in the main passenger side under the hood fusebox (see the diagram I've attached) ?

If that's the problem, it's called the Alternating Current Generator (or Alternator Circuit Generator; somebody please set me straight) fuse. If replacing it doesn't help, here are a few possibilities to explore.

what fuse? - HondaCivicForum.com

https://treehozz.com/what-is-acgs-fuse-honda


 

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