OK, this topic has been on my to do list for a while. For the longest time I though my Optimas just wouldn't hold a good charge anymore. It appears it is parasitic draw. This was slow with just myself, but I used vice grips to hold my meter leads to the cable and post.

I have a constant .20A draw. When I unplug fuse #14(Dome light, Courtesy lamp, Cargo Lamp, Running board lamp) it jumps to .35A for about 20 seconds then returns to .20 even though the lights are off.

The next one is one I think is the problem, #15(Stop lamp switch, GEM, PCM, 4 wheel ABS, Brake shift interlock, Cluster, PCM keep alive memory). Load goes from .20A to .03A unplugged.

What finally got me going on tracking this down is that my new Edge CTS Insight display is randomly staying lit up overnight with the key off. It seems the PCM isn't shutting off all the time.

Any idea of what to do next??

 

Pcm relay may be bad causing it to not power down.

 

Is the PCM relay under the dash or under the hood?

 

2001 and before its under the hood. 2002-2003 is under the dash

 

Ok, just found it in the owners manual. #30 PCM power relay. Is there a way to bench test it or just simply change it out?

 

I think it is square and is a bosch style relay. The diagram is on the side if it is. The new style iso relays are the small rectangular ones. The bosch style use terminals 85 & 86 for the coil. It should have some resistance on it but not a lot. When its in your hand, terminals 30 & 87a should have continuity and 30 and 87 should not. If you power terminal 85 & ground term 86, it should then have continuity on term 30 and 87. I think the blower relay can be swapped in its place.

Another thing that could cause pcm to not power down is if the windshield leaks and wet the gem.

 

Can you switch it with another relay, should be two under there. That should tell you if its good or not.

 

Thanks guys. I was just noticing that, one is for the blower motor and one for the IDM with the same part #. Gonna swap it with the blower motor...

 

Hmm, switching them didn't change anything. I removed it completely, same thing .20A draw...

On another note, I found that the radio and brake controller are pulling .02-.03A each...

 

I have had same problem and finally bought a new Edge, as I like to use it for read-outs, not to bump power, and I had purchased the first one used.

After that the new Edge no longer lit up on its own, but I still have random problem with parasitic load that is driving me nuts. Will be fine for weeks, then I will come out and batteries are low.

I am taking another run at it later today.

 

I bought the Insight new a couple weeks ago. I've actually had this problem for quite a while now...

Any other suggestions?

 

I am sure you know this, but when the Insight is lit, if you pull one fuse at a time, you will eventually pull the one to whatever is ailing your truck. The trick always to do the troubleshooting when it is going on, which is not always so simple to do.

 

How long does it take to kill the batteries?

 

Pull all the fuses and if still there you might have bad diode in alternator which still lets it charge while driving but drains when off so I pull the hot cable off alternator when chasing the draw

 

Given the OP is reporting only a .2 amp draw, it will take a very long time, if the batteries are fully charged to start with. Five hours to draw down one amp, maybe 100 hours to take one battery down to 50% discharge in a 200 amp hour battery. Rough estimate only here.