[urq] High beam indicator stuck on, high beam stalk has no effect- what did I break?

[Scott Justusson]

Dave?
Are you saying that reverse polarity on a diode equipped relay is more prone to sticking than a relay with no diode?  I understand a blown diode relay to be the same condition (albeit some melted bits from the diode included) as a relay with no diode.  IME with either, they tend to stick from an overloaded 30>87 circuit, not from the presence of diode or none.  IME2, the diode is really there to protect the switch and electronics from spikes, not many attribute the cause of relay sticking to the presence/lack of/blown diode.  

In Automotive Hella and Bosch diode equipped relays, the diode is in parallel with the coil. As such what I understand to be accepted theory and application, is that a diode equipped relay will have a lower half life than a non-diode relay, considered the cost of protecting upstream circuitry.

What do you know lad?  Do tell!

Cheers

SJ



-----Original Message-----
From: djdawson2 <djdawson2 at aol.com>
To: qshipq <qshipq at aol.com>; spotatashleys <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq <urq at audifans.com>
Sent: Tue, Jun 26, 2012 6:07 pm
Subject: Re: [urq] High beam indicator stuck on, high beam stalk has no effect- what did I break?


Look at diagrams online, you'll see both configurations stated as the norm.  Agreed on the arrow.

My original point was to indicate that reversed polarity in a relay using a diode may cause the type of behavior noted ("sticking" closed)... it has for me... and would be worth double checking.

Dave

 

 

 

-----Original Message-----
From: Scott Justusson <qshipq at aol.com>
To: djdawson2 <djdawson2 at aol.com>; spotatashleys <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq <urq at audifans.com>
Sent: Tue, Jun 26, 2012 4:51 pm
Subject: Re: [urq] High beam indicator stuck on, high beam stalk has no effect- what did I break?



To be even more clear, this internal diode pin-out position of 85 ground/86 power is always true for Bosch and Hella internal diode relays (Cathode to Pin 86 power)....   BUT, this is *not* a universal accepted or "world standard".  I have found quite a few internal diode name-brand relays that use cathode to pin 85.  Not too long ago, saw this very issue in a complex security system master relay box, where a tech replaced a non spec'd relay that was Cathode>pin 85, and EMF took out most of the controller board in short order.  The coil ohmed out correctly and the relay physically still worked, but the diode had already 'xsploded....

Best bet is to look on the relay circuit and point the diode arrow towards switched 12v+.  Thankfully, the accepted practice in reverse-bias diode protected relays is now to label terminal switched+ feed in addition to the diode symbol pointing to it.  It is also wise when retrofitting your Audi from a non diode relay to an internal diode relay, that you double check the 'ground' signal.  In many of the EWD in Audis you will find Pin 86 is ground in a non-diode relay circuit.  Just to add fun to it all....

Cheers

SJ


-----Original Message-----
From: djdawson2 <djdawson2 at aol.com>
To: qshipq <qshipq at aol.com>; spotatashleys <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq <urq at audifans.com>
Sent: Tue, Jun 26, 2012 1:58 pm
Subject: Re: [urq] High beam indicator stuck on, high beam stalk has no effect- what did I break?


You're right... 85 is ground.  Not sure how I botched those last 2 paragraphs to read the reverse.  Must have been too late last night.

Here we go:

Long story short, your relays will work if you apply signal (hot) to pin 86 and ground to pin 85, or the reverse.  But if there actually is such a tamper diode in place, polarity will matter, in which case you should insure that pin 85 is your ground, and pin 86 is your hot "signal" power that activates the relay.

If polarity is reversed (pin 85 hot signal, 86 to ground), the tendency for the relay to remain closed does exist.  I would make sure that you have 85 as your ground, and 86 as your "signal" hot.

Dave

 

 

 

-----Original Message-----
From: Scott Justusson <qshipq at aol.com>
To: djdawson2 <djdawson2 at aol.com>; spotatashleys <spotatashleys at hotmail.com>; s.b.mills <s.b.mills at gmail.com>; urq <urq at audifans.com>
Sent: Tue, Jun 26, 2012 7:26 am
Subject: Re: [urq] High beam indicator stuck on, high beam stalk has no effect- what did I break?



 
Dave, I double checked, then grabbed a few relays... and I really think you have this backwards....   Bosch and Hella relays with an internal diode, pin 85 is the ground feed = always.  This is also specified by Bosch (now Tyco) and Hella schematics.  To avoid making the basic mistake of blowing diode protection, I consider all Bosch/Hella relays (outside of the oem harness applications) to be 86 'Hot" and 85 "Ground".  A couple years ago, Bosch (tyco) started to supply all aftermarket relays with the diode to reduce the chance of installed EMF problems in newer cars.

The easy way to check a diode protected relay, is to check the schematic on the relay...   the tip of the "arrow" points toward the "cathode" (12v + voltage side).  I have never seen a Bosch (Tyco) or Hella Relay with cathode to Pin 85.  The good news is, you blow a diode by hooking the relay up wrong, it still works as an 'unprotected" relay.

The better news is that Audi (Bosch/Hella) and Volvo (Siemens) regularly use resistored 85>86 pin relays in the stock panels, which are better and longer lasting interrupts for controlling coil generated spikes.

Back to the switch, a properly operating switch could have the feedback problem.  Here it's more basic, the switch doesn't detent, which means it can't find low beam no matter how many diodes are in the relays.

Cheers and HTH

Scott J