Interesting dash bulb scenario

dave231 · 01-13-2009, 11:52 AM

I am new to the board and the 911 world. I want to thank all of you who post here as it has been a great help in repairing some of the issues with my 83 911SC.

I wanted to share my recent experience so as to possibly help some other poor soul working on his car. With all my searching I couldn't find this exact situation. My car was not charging so I went through all the suggestions and tech tips I could find on this site. After checking everything and nothing really needing repair I was at wits end and still had not found the problem. In addition the car was not idling very well and I had read all I could about CIS knowing that would have to be done as well. Since I had decided to tackle the CIS after the charging problem was solved that really became secondary in all my diagnosis to this point. Not really understanding the dash light and all of it functions I dismissed it as merely a blown bulb (think american car) and moved on the hard parts. To make my miserable story shorter I will say that the bulb must at least function for the car to charge properly. Apparently it completes a circuit necessary to excite the alternator in to a charge state. The great thing is my CIS now works wonderfully. I had not read where voltage affected the idle, only all the other issues (vacuum, sensors and so on). Once the voltage was brought up by the working alternator my idle quality was immediately restored. Now I only have a cold start issue that is really minor.

Needless to say, I was happy to spend .69 cents to fix my charging and CIS problems all in one! This is not my typical luck.

David

motorcop · 01-13-2009, 12:58 PM

Wow....I thought crazy s++t only happened to me! Glad you got it worked out. Do yourself a favor and go buy another bulb and throw it in the glovebox.

dave231 · 01-13-2009, 05:19 PM

Trust me. I bought 3!

Hugh R · 01-13-2009, 05:23 PM

What bulb? The alternator light bulb that comes on when the fan belt breaks?

DasBoot · 01-13-2009, 07:37 PM

I find this hard to believe. A 911's entire charging system can be disabled by a .27 cent bulb?

Hmm...

ramonesfreak · ramonesfreak's Garage

i believe i have read threads or posts on this same subject here somewhere and that its true

DasBoot · 01-13-2009, 08:01 PM

Quote:

Originally Posted by srandallf

i believe i have read threats or posts on this same subject here somewhere and that its true

I did a search and found this from "Early S Man": The warning lamp must work for the field windings to get their pre-excitation current.

Could be a loose or corroded connection at the warning lamp holder, corroded/oxidized lamp holder, corroded connection at terminal #11 of the 14-pin connector, fractured Blue wire under the insulation, or loose/corroded Faston connector at the brush holder of the alternator. Clean all of the above connections and see if that helps.

My suggestion, if the above doesn't work, is to run another wire outside the car from warning lamp to the engine side of 14-pin connector ... if the warning lamp comes on with ignition switch on, the you know the problem is between dash and 14-pin connector. If you have to run the 'new' Blue wire all the way to the brush holder D+ Faston tab to get the warning lamp to work, then the break in the wire is in the engine harness.

Wow. Learn something new every day.

And, what a crappy design!

ossiblue · 01-14-2009, 06:50 AM

Quote:

Originally Posted by DasBoot

I did a search and found this from "Early S Man": The warning lamp must work for the field windings to get their pre-excitation current.

Could be a loose or corroded connection at the warning lamp holder, corroded/oxidized lamp holder, corroded connection at terminal #11 of the 14-pin connector, fractured Blue wire under the insulation, or loose/corroded Faston connector at the brush holder of the alternator. Clean all of the above connections and see if that helps.

My suggestion, if the above doesn't work, is to run another wire outside the car from warning lamp to the engine side of 14-pin connector ... if the warning lamp comes on with ignition switch on, the you know the problem is between dash and 14-pin connector. If you have to run the 'new' Blue wire all the way to the brush holder D+ Faston tab to get the warning lamp to work, then the break in the wire is in the engine harness.

Wow. Learn something new every day.

And, what a crappy design!

Warren's legacy, once again, proves its value to those he left behind.

DasBoot and Dave231, you have personally discovered something more important than the solution to Dave231's problem, you found the treasure trove of information that is honored at the top of this page--Warren Hall.

Dave231, welcome to Pelican, and take a bit of time to search Warren's name and discover the depth and breath of his knowledge, as well as the depth and breath of the respect he has on this forum. He is truly missed by all.

kodioneill · kodioneill's Garage

with the blown bulb the alt wont charge as you know. the warm up regulator will not lean out when the alt is not working as it gets it's power from the charging circuit.

dave231 · 01-14-2009, 09:05 AM

Thanks LJ. I have read some of Warren stuff without realizing it. I appreciate all the posters here, it seems to be a great community.

Mattcamp · 01-14-2009, 12:44 PM

Anyone know if this problem is the same in newer 911's (2000-2001)?

A friend of mine just bought one and it has charging problems that the previous owner did not disclose. After calling him; he said that he never could figure out why he couldn't keep the battery charged. Nice guy huh?

mjshira · 01-14-2009, 01:24 PM

Quote:

Originally Posted by dave231

I am new to the board and the 911 world. I want to thank all of you who post here as it has been a great help in repairing some of the issues with my 83 911SC.

I wanted to share my recent experience so as to possibly help some other poor soul working on his car. With all my searching I couldn't find this exact situation. My car was not charging so I went through all the suggestions and tech tips I could find on this site. After checking everything and nothing really needing repair I was at wits end and still had not found the problem. In addition the car was not idling very well and I had read all I could about CIS knowing that would have to be done as well. Since I had decided to tackle the CIS after the charging problem was solved that really became secondary in all my diagnosis to this point. Not really understanding the dash light and all of it functions I dismissed it as merely a blown bulb (think american car) and moved on the hard parts. To make my miserable story shorter I will say that the bulb must at least function for the car to charge properly. Apparently it completes a circuit necessary to excite the alternator in to a charge state. The great thing is my CIS now works wonderfully. I had not read where voltage affected the idle, only all the other issues (vacuum, sensors and so on). Once the voltage was brought up by the working alternator my idle quality was immediately restored. Now I only have a cold start issue that is really minor.

Needless to say, I was happy to spend .69 cents to fix my charging and CIS problems all in one! This is not my typical luck.

David

great way to start learning these cars. I had a similar experience on my first 911 back in 1998.

Welcome to the community!

dshepp806 · dshepp806's Garage

simply: it's "part" of the circuit.......

good find!

Best,

Doyle

mlfox · 01-14-2009, 03:54 PM

Quote:

Originally Posted by DasBoot

I find this hard to believe. A 911's entire charging system can be disabled by a .27 cent bulb?

Could someone please post the part number of this bulb?

Regards,
mlfox