Jump to content

Recommended Posts

Recently the car has been giving the impression of a flat battery when trying to start. It would turnover a couple of times but very very slowly. Turning the ignition off and then on again and the car would turn over slowly and then speed up and start but this may take a few attempts. It gave all the impressions of a poor starter motor. But having fitted one on a previous Q7 I know this is a 4 hour job and even with a decent discount is still over £200 for the unit. So decided to ring a local auto electrician that could hopefully diagnose exactly the part that needed replacing. (Vagcom showed nothing amiss by the way).

 He turned up and checked the car over and said that the cars alternator was charging the battery at around 13.6v. This is a indication of a poor earth and fitted another earth cable from the earth point under the bonnet used for jump starting to the engine manifold. Said he’s fitted loads as it’s a well known problem within VAG that the earths corrode over time and need cleaning. The car now charges at just over 14v and starts better than it ever did less than 2 seconds from turning the key. Turns over faster than my mates 2011 and 2014 Q7’s. Cost £10 for the earth cable and £40 for callout Including 1 hours labour. 

Hope this is helpful to anybody with a similar problem.

 

 

  • Like 2
Link to post
Share on other sites
  • Trevor featured this topic

Thanks for the info Dave....very useful and I'm sure that it will help out loads of members experiencing the same symptoms.

It seems that earth points are the most overlooked part of the electrical system and so simple and cheap to cure.

Link to post
Share on other sites
  • 3 weeks later...
  • 10 months later...
On 10/26/2017 at 7:25 PM, Bigdave1230 said:

Recently the car has been giving the impression of a flat battery when trying to start. It would turnover a couple of times but very very slowly. Turning the ignition off and then on again and the car would turn over slowly and then speed up and start but this may take a few attempts. It gave all the impressions of a poor starter motor. But having fitted one on a previous Q7 I know this is a 4 hour job and even with a decent discount is still over £200 for the unit. So decided to ring a local auto electrician that could hopefully diagnose exactly the part that needed replacing. (Vagcom showed nothing amiss by the way).

 He turned up and checked the car over and said that the cars alternator was charging the battery at around 13.6v. This is a indication of a poor earth and fitted another earth cable from the earth point under the bonnet used for jump starting to the engine manifold. Said he’s fitted loads as it’s a well known problem within VAG that the earths corrode over time and need cleaning. The car now charges at just over 14v and starts better than it ever did less than 2 seconds from turning the key. Turns over faster than my mates 2011 and 2014 Q7’s. Cost £10 for the earth cable and £40 for callout Including 1 hours labour. 

Hope this is helpful to anybody with a similar problem.

 

 

Hi, which cable was replaced. As I’ve been told there is more than one earth cable? I believe I’ve got same problem

Link to post
Share on other sites
  • 1 year later...

Hi, thanks for the reply. Now how does this help with starting? I know the manifold inlet does not make contact with starter. Now does the negative lead terminal for jump starting making contact in another place with starter?

Link to post
Share on other sites

if you can please tell me how this help with starting if the two grounding points are not related to started or engine? its going from terminal lead to manifold bolt. unless the actual negative terminal lead its also linked to other grounds in the car? is that what it is? also what lenght wire and gauge do i need? 0/1 awg 2ft enough? can it go from negative to valve cover ground bolt instead because i have a v8 q7 and not sure if i have that manifold bolt you have there or may be at different location. i appreaciate your help and if you can answer those questions i will appreciate. 

Link to post
Share on other sites

😳 it’s negative don’t try it from the positive! You can go to any bolt on the engine as long as it’s not into anything plastic. I’m not sure what gauge cable it is as the auto electrition supplied it but you should be able to get one from any car spares shop. 

Link to post
Share on other sites

All negatives on the car are linked. The negative  terminal on the battery goes to the body of the car. The negative from the starter goes to the body that’s why they are called earths/earth straps. The problem isn’t the positive as that’s a dedicated wire that indirectly goes straight to the positive terminal on the battery. The negatives/earths at the bottom of the engine are open to the elements and corrode against the body and as such mean that the system can’t make a good circuit. By putting an extra earth/negative at the top of the engine the you are improving the circuit. You could just get a jump lead and connect from the terminal in the picture to anywhere on the engine to see if it cures your fault.

Link to post
Share on other sites

Hello Dave,

Many thanks for the detailed explanation, and hopefully the logic of the importance of good body/chassis earths will now be clear. 

Only one point that I would clarify - ‘The negative lead (earth in my words) from the starter goes to the body......’.

Is this something unique to the Q7, since generally - where the engine is earthed via. its own substantial earth lead, the starter will pick up a good earth from is substantially bolted connection to the engine? 

Kind regards,

Gareth. 

Link to post
Share on other sites
  • 3 weeks later...

I had, what some describe as, a "lazy starter".  Symptoms?  Highly inconsistent.  Include:  failed to start - regularly.  Start sequence stopped after about 4 turns.  Turning the key again resulted in the same failed start. Over and over until battery died.  Putting jump starter cables to another car GENERALLY enabled the starter to start the engine on my beast.  Why?  Not really sure.  Maybe higher V courtesy of donor car power = higher turnover..  But getting a jump-start for a Q7 from another car ever second / third / fourth start is not ideal.  A pain in the @$$ if you ask me!! 

The refusal to start was highly inconsistent.  First manifested itself after a 2 hr drive when the car had been stopped for only 10 mins.  Diagnosis: starter failed.  Apparently a relatively common problem in the Q7 - the ECU only turns on fuel when starter has the motor turning at requisite RPM.  Insufficient RPM, no fuel = no start.

Anyway, real pain in the @$$ to change too but a local mechanic sorted it out for me.  Audi would have made the repair worthless...

Well, it starts much quicker now with the new starter.  But I should probably have replaced the alternator (as it comes out before the starter does). Time will tell if this is a fix for my beast.  Now, just got to figure out if there's a way for to stop it belching out as much black smoke when I put the foot to the floor...

Link to post
Share on other sites
  • 4 months later...

Hi Dave, interesting article this. This has been happening on my 2014 q7 for four years now, never failed to start but very lazy on the odd occasions.

We now see the boot lid not opening or closing on the key fob but ok to open from the door switch. No boot light will eliminate which is the sign that it will be lazy to start.

Today the boot has failed three times !

Could this also be linked to the earth strap failing, no error codes present.

 

Your thoughts please Dave would be appreciated 

Link to post
Share on other sites
  • 2 weeks later...

Just back from the mechanics , he told me to google earth wire and just saw this thread. Wish I’d know about this before to try it as I’m replacing batteries every 2 years . Same problems slow starting or not starting at all. Carry jump leads permanently. We all know replacing the battery is costly due to the labour involved. He suggested I purchase main dealer earth wire and he would fit it . Any other advice ? 

Link to post
Share on other sites

My mates Q7 just had a funny problem where the battery would go flat over night maybe once every couple of weeks. Battery tests fine and couldn’t fathom out why it was doing it. Turns out it was the auxiliary heater fan that was kicking in by itself during the night ( the auxiliary heater wasn’t turning on it was just some sort of fan associated with it) only reason it was found was one morning when he went out to it he could hear the fan before he opened the car. Pulled the 20A heater fuse on the passenger side of the dash board and it’s been fine since.
Auxiliary heaters seem to be a bit rubbish on these anyway. If you run the car low on fuel and they try to kick in they lock up and need vcds to unlock them so most Q7’s aren’t working.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...