I am diagnosing an electrical problem and need some help with my diagnostic procedure. I was seeing a small battery drain and placed an ohm meter across the battery cables (battery disconnected). I read 23k ohms.

When I opened the drivers door to pull fuses the ohm reading went to 0.7 ohm. I think there must be a short in the door switch system (note: same response with any door opening).

If I pull the CTSY fuse then the ohm-meter continues to read 23K ohms. Pulled all remaining IP fuses one at a time and reading stays 23k-ohms.

While I look for the short in the door switch system (I should not have a near zero ohm reading across the cables at any time - right?) can anyone help me figure out how to diagnose the 19k-ohm resistance across the battery cables?

Thanks for the help. This is my main task for today and any assistance is appreciated.

Kevin

Is it possible that the CTSY circuit is suppose to work by shorting power to ground when a door is open?

I checked a number of other circuits at the fuse panel with the fuses plugged in. Below is what I found. These readings are with the ECM, tailgate and under-hood light disconnected and drivers side DOOR OPEN. I've had similar problems with a bad ECM and wanted to rule that out.

23.7K-ohm :
pwr/accy (circuit breaker); stop/haz; pwr/aux; 4wd; ctsy (fuse in); rr defog; a/c comp; pk lps; ecm/bat; drl/fog;

.952K-ohm : Pwr/wdo (circuit breaker); htr a/c; brake

68.1-ohm : crank

.741k-ohm : trans

1.1-ohm : gauges; ecm/ign; turn b/u; airbag; eng

10.4K-ohm : radio; wiper

0.7-ohm : illum; ctsy (when fuse pulled)

OL - RDO BATT

So somehow the door switch circuit which is powered from the ctsy fuse causes a short to ground for that circuit. Does anyone have any idea how to isolate parts of the ctsy circuit?

HELP!!!!!

Reading wiring diagrams I see that the circuits with 10.4k-ohms of resistance are feed power through the BRN wire of the ignition switch and the circuits with .952k-ohms of resistance are feed power through the ORG wire of the ignition switch.

The crank fuse receives power from the yellow wire of the ignition switch and feeds the park neutral switch and the DERM.

 

What are you hoping to get out of reading the circuit resistances? You need to measure amperage, not resistance.

The amp draw should fall to below 0.035A (35mA) after everything has gone to 'sleep', 20-30 minutes with the doors closed.

 

my understanding is/was that there should never be low resistance across the battery cables unless there is a short to ground in the system and that shorts to ground should be eliminated before doing amp draw testing. The 0.7ohm resistance across the cables (unconnected from the battery with the door open) led me to believe there is a short.

Do i have this wrong?

If I am correct than I should not see continuity between the orange wires on the CTSY circuit and the white wires on the door lock circuit. But I do - with only 0.7ohm resistance!

 

I put my craftsman multimeter model 82040 on the mA scale. AMP draw information. Total amp draw is 6.77mA:

Stop/Hazard is 0.59 mA
RDO/Battery is 1.15mA
PK LPS is 3.28mA
ECM/BATT is 0.6mA

Remaining AMP draw after all other fuses and circuit breakers in IP remaining is 1.13mA. Are there any non-fused circuits to check?

 

What is the amp draw at the battery? If it is below 35mA, then you do not have an excessive power draw and the battery is likely at fault.

 

This is a new battery (days). I did find a short in the door switch wiring running under the carpet. It appears that the white wire is sometimes shorting to power and sometimes to ground. I found this by moving the wire bundle I still have not found the chaffed wire.

AMP readings. Straight from the multi-meter manual. "NOTE: lf your meter does not work properly, check the fuses and batteries to make sure they are still good and that they are properly installed."

Sure enough two blown fuses and the batteries are run down. Interestingly enough the meter "works", but gives wrong answers when the fuse is blown. I would have thought "no answer" would be the default. New fuses purchased and I'll get back in the garage this weekend to get real AMP readings.

 

After repairing some splices in the wiring harness that runs under the drivers side carpet to the rear of the jimmy I'm back in business. I remeasured AMP draw at the battery and I am seeing .007A.