Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Engine stumble/lights flicker - voltage problem?

Recommended Posts


The weather is getting nice and I decided to do some work to my car prior to pulling it out for the spring. My interior lights were flickering prior to winter storage. I knew that my alternator bearing was wearing out so I decided to replace the alternator hoping to fix two birds with one stone. After I replaced the alternator... this is what happened...


The interior lights still flicker (see instrument cluster lights and overhead light) and the engine appears to stumble in conjunction with the voltage drop. As you can see the voltage gauge it moving from 13 to 14v. Any ideas???

Update: Battery load tested good.

Link to comment
Share on other sites

From your video looks like your regulated voltage is too high, that replacement alternator could be bunk!

I would verify the voltage with a meter. Or go out to a local auto shop /store that can give you a charging system check. To verify

Hope this helps

Edited by EleCTriCT
Link to comment
Share on other sites

First and foremost, there is no mention of battery testing or replacement. That would be the first place I would look.

Have you looked at all of the main power leads? These are the ones that are normally suspect (corroded or poor connection).

Main positive from alternator to starter to jump point in engine bay.

Ground strap from engine to chassis.

Ground strap from battery to chassis.

There are others as well but much more difficult to access...

Main positive lead from battery to main fuse box.

LONG Positive lead from fuse box to junction above transmission.

Positive lead from junction point to jump point on engine.

Link to comment
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.

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...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.