Reconnecting the Battery in an Aston Martin DB9

If you’ve been good boy [or girl] and disconnected your battery during a service event like you were supposed to – kudos to you for taking the time!  Or perhaps you are changing your battery and it’s time to hook it up.  Whatever the reason, you’ll want to follow the rights steps to get your DB9 operational again.  Even after you hookup the battery there are a number of steps you need to follow to reset a bunch of the modules.  I will reveal all below.

Of course to get to this point I’ve done some work.  Check out my other article and video on Disconnecting the Battery.

Tools Required

craftman-8mm-combination-wrenchYou only need a few tools for this project:


Battery System Section 14.01 in Aston Martin DB9 Workshop Manual CoverThe Official Aston Martin Workshop Manual Section 14.1 on the Battery System covers it in just 3 steps and doesn’t really cover the few bits of nuance.  I will be a bit more verbose below.

This process should take you about 10 minutes to complete.

Before you start I guess we should talk about the condition of the battery terminals and clamps.  a-corroded-battery-terminalIn some cars these can become covered with a layer of corrosion.  My car has lived in California for the 12 years of its life, and as you see in the videos below, the cable and terminals look like new.  If yours are needing some love, clean them up before proceeding.

In my case I had only removed the negative battery terminal to work on Changing my Spark Plugs and Coil Packs, but if you’ve had your Positive terminal or battery removed, connect the positive terminal as shown in my “Changing the Battery” video [coming soon].  We connect the positive terminal before the negative to reduce the risk of damage [a.k.a. shorting the crap out of everything] with an errant wrench motion.

  • reconnecting-the-battery-in-an-aston-martin-db9Connect the Negative Battery terminal.
    • Push the negative terminal down tight over the negative post on the battery, and perhaps give it a wee twist as you wiggle it down.  Should be no need for a hammer.
    • As soon as you make the electrical connection, you’ll probably hear a bunch of noises in the rest of the car coming to life (even with the key off).  The CD changer may start to index, etc.
    • Use the 13mm box end wrench and snug up the terminal clamp. No need to over-tighten this, just ‘snug’ is good. [The Official Aston Martin Workshop Manual lists a specific Torque of 9 Nm, but in this case I went with my own ‘feel’]   When done give the terminal a tug and twist to make sure it’s solidly attached and won’t move.
  • Battery Compartment Cover in an Aston Martin DB9Place the battery compartment cover loosely in place.
    • You need to take a little care here, you don’t want the aluminum plate dinging up your leather.
    • Swing the back down and into position first, then lower the front lip into the slot.  This is really best seen in the video below rather than me describing it.
  • Start each of the ten (yes, 10) cover retaining bolts loosely first.
    • Be careful not to drop anything into the gaping fender opening on the left side. If it falls in there, it’s lost forever and will rattle around driving you nuts.
  • Next I used an 8mm socket on a nut driver to speed most of the bolts along. A few you may need to do by hand. Just snug them up.
  • Small Torque WrenchTorque each of the bolts to 8 to 12 Nm. [in retrospect another review of the Official Aston Martin Workshop Manual says the Torque spec should be 9 Nm (7 ft lbs)]
    • I set my Torque wrench to 10 Nm (7 ft lbs).
    • I couldn’t easily get my torque wrench on all of the bolts (I could have tried harder) so you’ll see me just snug up a few with a smaller ratchet in the video.
    • For a couple on the left side I needed to use just an 8mm combination wrench.
    • I’m not sure the torque spec is essential here, but they just don’t want them loose (and rattling), or over-tightened where you’d twist loose the captive nuts.
  • Right Rear Seat Lower Back of an Aston Martin DB9Replace the lower seat back insert.
    • It just has four (4) Velcro pads you need to line up and press back into place.
    • It only fits one way (easily) so if its fighting you, just turn it over and see if it lines up better.  Simple.
  • Right Rear Seat Base of an Aston Martin DB9The final step is to replace the seat bottom cushion.
    • Again be careful working this into the space.
    • It’s held in place by a long Velcro strip along the front edge, so lower the back edge into position as you swoop the front in and down. Again, check out the video to get a clearer picture of this.  Also simple.

That’s it for the battery re-connection, but you still have four (4) more procedures to follow.  As pointed out in Aston Martin Service Bulleting SB153 anytime you’ve had the battery disconnected you need to:

The first three steps are easy, only take a few minutes and I have also included links to their videos below.  The engine misfire correction factor relearn is important (check out my article on this), but has to be done on the highway.  I have a detailed video on this process as well.

OK, full disclosure here. I wanted to share my experience of reconnecting my battery after having it disconnected for 3 days while I changed my Spark Plugs and Coil Packs.  Somehow, even though my battery was disconnected, it became significantly discharged (weak). When I hooked my battery back up and attempted to restart my car, all sorts of weird sh!t happened. The engine barely turned over, and when it did finally start it stumbled along like it was on life support. Even more scary, all sorts of weird electrical things started to happen after I shut it off. Both the driver and passenger side mirrors started endlessly ‘hunting’ around moving on their own, the CD changer kept indexing, lots of crazy stuff. I couldn’t stop it, and had no idea what to do. After a few minutes of this I then panicked and pushed the Battery Disconnect button in the trunk, no change. The mirrors kept wigging out, so I had no choice but to set a new world speed record for getting back in and disconnecting my battery (about 3 minutes, to get it all back apart again). On a hunch I calmed down, charged the battery for 2 hours, pressed the battery reset button and then put it all back together again. Complete success the second time around [whew!]. So, a weak battery is no fun, and many of the electronics ‘modules’ like the door mirrors wig out with they get less than the proper voltage. Turns out three months later the battery finally gives up (after 12 years of service), and I’ll have an article on that soon.

OK, here is my video on the battery re-connection process.

Setting the Clock

Recalibrating the Seats

Re-calibrating the Door Window Glass Auto-drop

Relearning the Engine Misfire Correction Factors

4 thoughts on “Reconnecting the Battery in an Aston Martin DB9

  1. Pingback: How to Change the Coil Packs and Spark Plugs in an Aston Martin DB9 – Aston 1936

  2. Jim Farmer

    I have a UK RHD 2009 DB9 in at my bodyshop for the last 5 weeks. The battery has drained, I used my trickle charger on it so it is now back to full charge. However I now have an immobilser error (from OBD reader), the car just clicks the starter solenoid when trying to fire up. I do not have the battery reset button, a relay is in it’s place with no buttons etc…to press to reset. however, I have disconnected the battery for 30 mins, reconnected and left for for 10 mins – still same. It seems the car has lost it’s memory and it is taking my mind with it! I have closed all doors, boot, bonnet then locked the car, then unlocked and still no change. Tried the battery isolator switch on and off – still no change.
    Any ideas to help?


    1. Hi Jim,

      I’m not sure I have any savvy advice to help. Honestly if you hear the solenoid click, do the dash lights dim during the click. When my battery went south, it died something like this. Enough power for some ancillaries, but when I pushed the button I got no love. Charged fully, but still bad enough to not start. You could try boosting it to see if it starts. If it does, your battery is shot and time for a replacement.

      Hope this helps a bit,


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