ECM battery malfunction after replacing battery (2 Viewers)

[sleepdoc]

A couple weeks ago I was having battery issues in my 01 cruiser. Drove by Autozone for a battery check, it was bad, replaced right then and driving away my CEL came on. Drove a couple days thinking computer needed to relearn my driving but it stayed on. Autozone said their battery is good when I went back to question them. I cleaned the terminals of old corrosion and light went off. Well, it came back on today and I don't know what to do. Any idea if this now two week old battery could cause CEL to come on? It seem too coincidental for it to be anything other than the battery. I unhooked the terminals this afternoon and tried again with no luck.
Thanks

 

[Trunk Monkey]

What's the CEL code?

 

[sleepdoc]

What's the CEL code?

P1600. My mechanic said its a "BS code" but it must be caused by something. Google says ECM is getting charge from the battery even with ignition off.

 

[sleepdoc]

I wondered about my phone charger in cigarette lighter causing an issue but removing it did not change anything.

 

[Rhetoric]

This could be useful to you:

P1600 - ECM BATT MALFUNCTION

2000 Cruiser with immobilizer bypass mod installed approx 3 months ago. The light came on this morning after my brother pulled the battery to jump another car. Where do I check first? Is this related to the bypass? Code won’t clear with TechStream.

forum.ih8mud.com

In addition: your "mechanic" sounds like BS. A real mechanic would want to solve this and not write it off, sending you into the depths of this place.

 

[medtro]

Which year model? Do you have any modification done to the fuse box?

 

[sleepdoc]

It’s the 2001. I do think I had an immobilizer bypass installed in 2020.

 

[sleepdoc]

This could be useful to you:

P1600 - ECM BATT MALFUNCTION

2000 Cruiser with immobilizer bypass mod installed approx 3 months ago. The light came on this morning after my brother pulled the battery to jump another car. Where do I check first? Is this related to the bypass? Code won’t clear with TechStream.

forum.ih8mud.com

In addition: your "mechanic" sounds like BS. A real mechanic would want to solve this and not write it off, sending you into the depths of this place.

I appreciate the suggestion. I wonder what the resolution of this was?

 

[BamaHoo]

My recent thread may help as well:

Need help with P1600 Code

I need some guidance on troubleshooting a P1600 code on my 2000 LC. Saturday morning I replaced the PCV valve, grommet, ventilation hoses, vacuum hoses, and most of the vapor hoses at the charcoal canister. Was feeling good about it, especially since I was able to retrieve the PCV grommet in...

forum.ih8mud.com

I took a pretty deep dive on how to troubleshoot this issue before I figured out the obvious cause of mine (I had removed the EFI fuse when I direct-wired power to the EFI relay, which also had the effect of turning off the "always on" power to the ECM BATT terminal on the ECM). The FSM and the EWD should give you the information needed to determine if the problem is in the ECM or the ECM circuit.

 

[sleepdoc]

After all these awesome tips and links I ended up adding a fused wire from open relay slot to the open number 3 slot on the EFI relay location. As @BamaHoo said, bypassing the immobilizer had turned off the always on power to the ECM battery. I do not understand why it took replacing my battery to make this throw a code after having the bypass there for five years, but the code is gone! I appreciate all the help.

 

[sleepdoc]

Well, it was a good couple of days but now will crank but not turn over...seems like the bypass isn't working any more. I have checked the fused wires and fuses are good. Worked this morning to get me to work but now its not. I have replaced the fused wire I just added and checked all connections on the bypass. any ideas?

 

[sleepdoc]

Hard wired the bypass to the battery. Now it has all time power. Starts right up.