Menu toggle

3.2 Battery & DME Relay

N

nixon

New member
Hello, hoping you can help. My first post! My 3.2 broke down for the first time in almost 7 years at the weekend. Started ok in the morning then after sitting for 5 hours after 100 mile drive would not start. Battery test concluded bad cell. AA man then concluded coil had live feed but was not switching. I'm a bit of a novice mechanic but from what I've read i will be trying a new battery and DME relay. Bentley manual notes the battery should be 88Ah but those i have seen online (Eurocarparts, Halfords, etc) suggest batteries with lower rating. The present battery is just 68Ah. I would be grateful if anyone can advise what spec. battery I need. Similarly the DME relay on the car is annotated 911 618 154 00 / 898247 / 12V / 15A whereas the replacements are marked 12V / 30A. I am no electrician but there is clearly a big difference between 15A and 30A. Can anyone explain what relay i need? If new battery and relay don't fix it i would be very pleased if anyone can suggest other things to check? Thank you Tim
 
I have had crank sensors fail Tim due to corrosion in the alloy bracket (top of bell housing) usualy after getting hot, sometimes re-start when cold but soon to fail again! New sensor and bracket required if that is the case.
 
If not cranking when hot but will bump start easily check the earth strap from transmission to body. I had hot start issue on way back from Classic Le Man's one year after a long period. Car would not start when hot but OK after it cooled. Checked earth strap looked OK but when lifted up off suspension tube was showing a lot of corrosion. Replaced and not happened since
Hope you find it quickly to make use of whatever decent weather we have left[:)]
 

ORIGINAL: nixon

Hello, hoping you can help. My first post! My 3.2 broke down for the first time in almost 7 years at the weekend. Started ok in the morning then after sitting for 5 hours after 100 mile drive would not start. Battery test concluded bad cell. AA man then concluded coil had live feed but was not switching. I'm a bit of a novice mechanic but from what I've read i will be trying a new battery and DME relay. Bentley manual notes the battery should be 88Ah but those i have seen online (Eurocarparts, Halfords, etc) suggest batteries with lower rating. The present battery is just 68Ah. I would be grateful if anyone can advise what spec. battery I need. Similarly the DME relay on the car is annotated 911 618 154 00 / 898247 / 12V / 15A whereas the replacements are marked 12V / 30A. I am no electrician but there is clearly a big difference between 15A and 30A. Can anyone explain what relay i need? If new battery and relay don't fix it i would be very pleased if anyone can suggest other things to check? Thank you Tim
Click to expand...
Hi Tim
Go for the 88Ah battery only £10 more and one can never have a enough power. The DME relay is under the pass seat next to the ECU and a good time to change it. But i think you need to change the TDC and speed sensors on the N/S top of the gearbox bell houseing not the easiest of jobs and they need a 1mm gap as in the Bentley manual.
 
Thank you all for your thoughts.

When there is life in the battery the starter cranks ok but won't start. I have not tried bumping it. Is jumping it something to avoid, might it do damage?

Charles, when you say not the easiest of jobs is it a job for a novice? I am keen to get to know my car better but wouldn't want to attempt a job beyond me. How are these sensors accessed? Should it take 10mins or 10hrs?!! As regards the relay, are replacements 30A? Thank you Tim
 
The 30A is the rating of the relay contacts - not the amount of current they consume! Therefore a 30A relay will switch twice the current of a 15A relay, so the contacts will last longer.
 
Richard, I was happy that a 30A relay will do the job of a 15A one but was suspicious I was being offered the wrong relay altogether. I understand the relay is actually 2 relays in one box - one serving the fuel pump and the other the DME? Thanks Tim
 
I just looked at the spare one I carry in the glove box. My indy got it for me from Euro Car Parts, and their reference number is 450.33.0390. On the box, it shows the manufacturers name as KAE, and their part number 3.308.100. On the relay itself it shows the part number, and 12VDC / 30A.

Hope this helps.
 

ORIGINAL: nixon

Thank you all for your thoughts.

When there is life in the battery the starter cranks ok but won't start. I have not tried bumping it. Is jumping it something to avoid, might it do damage?

Charles, when you say not the easiest of jobs is it a job for a novice? I am keen to get to know my car better but wouldn't want to attempt a job beyond me. How are these sensors accessed? Should it take 10mins or 10hrs?!! As regards the relay, are replacements 30A? Thank you Tim
Click to expand...

I can do this job on my lift in about 2.5hr. so you will be on your back i guess, you will need to jack up the N/S/R and remove the wheel to work in that gap, cover the brake disc and caliper they will make you dirty, Good lighting is a must. 4hr !!
 
New DME relay and I'm up and running again. I'll be carrying spare in future! - Thanks for your help. Tim
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top