Electrical Draw???

[Smokin6-0]

Well, in the last few days my 97 ZF5 truck has started killing the batteries over night. The batteries are only about 9 months old and I haven't touched anything on the electrical system. I am thinking that the truck must have a parasitic draw of some sort. This is obviously a substantial draw to completely kill both batteries over night. Would someone be so kind to walk me through how to test for this draw and pinpoint it?

 

[Patrick Feeley]

Usually I would disconnect both battery positive leads and then put an ammeter in between one of the disconnected positive cables and the corresponding battery post. Then I would start pulling fuses and see which ones get rid of the draw when pulled. After you figure which circuit it is, the fun begins! An Electrical and Vacuum Troubleshooting Manual (EVTM) would be extremely helpful from this point. Cheers!

 

[Racer X]

Usually I would disconnect both battery positive leads and then put an ammeter in between one of the disconnected positive cables and the corresponding battery post. Then I would start pulling fuses and see which ones get rid of the draw when pulled. After you figure which circuit it is, the fun begins! An Electrical and Vacuum Troubleshooting Manual (EVTM) would be extremely helpful from this point. Cheers!

:whs:

One thing to know when using this method - There will always be a very small current draw by the PCM to maintain memory. Also the clock in the radio/stereo and other factory options your truck may have such as keyless entry/anti theft system, under hood light.