[W126 Coupe] Strange gauge lights error, any ideas?

[Markus Meyer]

I'd ask for my money back.  You may just get another junk one back. BTDT.

On Thu, Feb 25, 2010 at 5:43 PM, Josh Allen <heyallen at null-ptr.net> wrote:


> If I were going to have to pay for the replacement, I'd definitely be

> looking for an AL129X alternator to swap in, but it's still under warranty

> so it's just going back to Napa.  They said they'll have one for me

> tomorrow, I just need to bring in the failed one and the receipt for it.

>

> -Josh

>

>

> On 2/25/2010 1:38 PM, Markus Meyer wrote:

>

> Suggestion, as I just went through a similar test.  I have several 126's,

> so I just stole the alternator from my SEC to keep my wife's SEL going,

> since the SEC is hibernating right now anyway.

>

> I about to get a Bosch AL129X alternator from the yards, found on late

> 80's, early 90's SAABs.  Same housing, 115 amps vs. 80 amps.

>

> I've been told most rebuilds are junk, so just be aware.  Dealer wants

> close to $350-400 for one!

>

> Markus

>

> On Thu, Feb 25, 2010 at 4:35 PM, Josh Allen <heyallen at null-ptr.net> wrote:

>

>> Ok, I think I've found the issue.

>>

>> I followed the suggestions of the ETM and a few others here, tested the

>> resting voltage (12.3v), idle voltage (13.7v), and voltage with various

>> electrical loads on (13.4v).  I then ran up the RPM with the loads (13.9v

>> max), and without (14.2v max).

>>

>> I then hooked up my oscilloscope and checked the B+ waveform, as the ETM

>> suggests, to look at the condition of the rectifier bridge inside the

>> alternator.  It came up with an obvious missing phase in the waveform, so it

>> appears that one of the diodes has failed.

>>

>> I've attached a pic of the waveform on the scope, for those who might find

>> it of interest.

>>

>> Thanks for all the suggestions, now I get to do battle with the parts

>> house!

>>

>> -Josh Allen

>>

>

>

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