Matronics Email Lists :: View topic - Fried EXP2BUS was EXP2BUS and non-functioning alternator

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Fried EXP2BUS was EXP2BUS and non-functioning alternator

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

vshimsl(at)live.com
Guest

Posted: Sun May 03, 2009 4:22 am Post subject: Fried EXP2BUS was EXP2BUS and non-functioning alternator

.hmmessage P {margin:0px;padding:0px;} body.hmmessage {font-size:10pt;font-family:Verdana;}        .hmmessage P {margin:0px;padding:0px;} body.hmmessage {font-size:10pt;font-family:Verdana;}   Hello C



Simple Things revisited.



Do you have a thick cable going from the engine case to the negative return on your battery? I used a thick braided mesh cable to the firewall and from there a thick Van's 3/8" diameter (I think) to the battery.



The reason I ask is that an ohmmeter check will show continuity possibly through some round about way C but the engine is electrically isolated from the engine frame by the rubber 'Lord' mounts and you need as thick a cable (electronically speaking) returning to the battery (neg) as leaving it (Pos)



Also check the ground return for your 'EXP BUS'. From the block diagram at 'ControlVison' it is needed for the relays and internal over voltage module to work properly. Ideally measure the voltage from the battery neg terminal to the EXP BUS ground. It should be zero VDC C anything else indicates a poor ground. Speaking of the  EXP BUS internal over voltage protection C a poor ground could affect its operation causing it to erratically shut down the alternator. This would appear to you as a defective alternator.



Next the alternator:



Try the following with the engine NOT running.

Measure your battery voltage exactly. Next disconnect the 'T' connector at your alternator. Turn on your master and alternator as if it was connected (Engine NOT running) and 'again' measure the voltage on the 'IG' pin of the connector. Now measure the 'L' pin voltage.



The pin that reads the same voltage as the battery should be your 'IG" lead. The one that reads the battery voltage minus ~.7VDC should be your (LED) 'L' lead. These were my readings using a Fluke digital multimeter.



Failing this C remove the alternator and take it to an auto-electrical shop and ask them to bench test it. If it passes C you will know your problem lies elsewhere.



EXP BUS



If the alternator checks out good C then the next item on the list of suspects is the EXP BUS Internal Over Voltage Controler. As a test C hook up a temporary Alternator switch ('IG' lead) to bypass the EXP BUS. Fire up the engine to see if all is well carefully monitoring your voltage to make sure you do not in fact have an over voltage condition. If you alternator works you now can narrow in on the EXP BUS wiring C and then finally C the unit itself.



The idea is to divide and conquer. Still I suspect in the end you will find that it boils down to a simple wiring error. At least that has been my experience

Good Luck C



Vince H.

Washington State - USA

N8432

RV8 - Ready for Final Inspection





 	  Quote: 	
		   Thanks Ed.  I'll check for any signs of high current.  I was able to

 check the power at the alternator and the 12V is getting to the right

 pin C the warning lamp lead is connected to the right place (and showing

 about 1V C not sure if that's what you would expect to see the other side

 of a 12V LED) but it "felt right".


	


Insert movie times and more without leaving Hotmail®. See how.  [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum