bladenbullet
Member
- Joined
- Feb 3, 2015
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- 35
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the modules in a vehicle can take up to 45 minutes or longer to shut down when performing a draw test...disconnecting the cables can shut off a potential draw and make it hard to find also...a shunt should be installed that can allow the vehicle to be operated and all accessories engaged then with an ammeter attached the shunt is opened so there is no interruption of power...then wait for the modules to shut down and get an accurate reading... https://www.amazon.com/Thexton-431-...coding=UTF8&psc=1&refRID=9RZA27BA3DDJMTS545BQ
if a shunt isnt available a sensitive inductive pickup can be used...
if a draw is found voltage drops can be performed across fuse terminals to determine which ciruit is drawing without removing the fuses....this way you wont lose a draw by removing a fuse and have to start over again....any fuse with current running through it will have a slight voltage drop due to connections at the terminals...
these vehicles are known for bad battery cables causing poor connections...a voltage drop across connections will reveal that concern...battery cables are expensive if thats the case...i corrected the problem on my own by sweating the terminals to the cables with solder 3 years ago and solved the problem for good..
a voltage drop is performed by setting the meter to volts and placing one lead on each side of a connection...then crank the vehicle (fuel pump or ignition bypassed-preferably fuel pump so you arent loading cylinders with fuel)...no connection should read more than .1 volt drop and a good connection will usually read in the hundreths of a volt...you can put one lead on a cable end and the other on the bare cable going into it to check the connections there....i was losing 1.5 volts through one of my cable ends and several were in the .5 volt range...drop was non-existent after soldering...
under load you would be surprised how much a bad connection will drop...i had a student who replaced a starter, battery and alternator on his vehicle...in 30 seconds we determined he had a bad ground connection losing 4 volts and corrected it in another 10 minutes....its a test that isnt performed often enough and reveals quite a few problems...
good luck...
if a shunt isnt available a sensitive inductive pickup can be used...
if a draw is found voltage drops can be performed across fuse terminals to determine which ciruit is drawing without removing the fuses....this way you wont lose a draw by removing a fuse and have to start over again....any fuse with current running through it will have a slight voltage drop due to connections at the terminals...
these vehicles are known for bad battery cables causing poor connections...a voltage drop across connections will reveal that concern...battery cables are expensive if thats the case...i corrected the problem on my own by sweating the terminals to the cables with solder 3 years ago and solved the problem for good..
a voltage drop is performed by setting the meter to volts and placing one lead on each side of a connection...then crank the vehicle (fuel pump or ignition bypassed-preferably fuel pump so you arent loading cylinders with fuel)...no connection should read more than .1 volt drop and a good connection will usually read in the hundreths of a volt...you can put one lead on a cable end and the other on the bare cable going into it to check the connections there....i was losing 1.5 volts through one of my cable ends and several were in the .5 volt range...drop was non-existent after soldering...
under load you would be surprised how much a bad connection will drop...i had a student who replaced a starter, battery and alternator on his vehicle...in 30 seconds we determined he had a bad ground connection losing 4 volts and corrected it in another 10 minutes....its a test that isnt performed often enough and reveals quite a few problems...
good luck...
