Changing Battery, OBD2 Battery Keeper 1998 v70

[MrAl]

I’ll double check the back feed on the OBD to ECU after a coffee in the morning

Hi,

Oh ok thanks. Just be careful I wouldn't want you to lose your monitor readiness.

With the amount he drives? If they don't go ready, they never will! =)

Oh right, ha!

[wizechatmgr]

Hi,

Very good catch. Those bulbs could draw 500ma each and there are several. That would put a strain on the wiring.
I guess we have to keep the doors shut.
Anything else you think might draw current?

Make sure key isn't left in ignition - I know, it sounds obvious... We had an experiment a while ago where if the chip for the key is left present, some modules won't turn off or will and then turn themselves on intermittently. Doesn't matter the key position either. Mere presence of the chip does it if I remember correctly.

[abscate]

There is even a P code for “key left in too long “ which pends when you do the key/antenna trick on a 1999 immobilizer.

My recollection on the 1999 is the OBD power buss is through the CDM (or DDM as it’s also called ) so generally that won’t back feed to the ECU supply.

I would just 12 volt to the kidney fuse box bolt and a ground

It’s not trivial to remove the battery and keep 12 volt on the bus but it’s possible; I had to do it on Shagg once for inspection , to swap batteries

[MrAl]

Hi,

Very good catch. Those bulbs could draw 500ma each and there are several. That would put a strain on the wiring.
I guess we have to keep the doors shut.
Anything else you think might draw current?

Make sure key isn't left in ignition - I know, it sounds obvious... We had an experiment a while ago where if the chip for the key is left present, some modules won't turn off or will and then turn themselves on intermittently. Doesn't matter the key position either. Mere presence of the chip does it if I remember correctly.

Hi,

Mine doesn't have a chip in the key but I'll do that anyway. I usually remove the key every time I get out of the car. Rare times when I leave it in on purpose like when I have to keep the engine running and get out for something.

[MrAl]

There is even a P code for “key left in too long “ which pends when you do the key/antenna trick on a 1999 immobilizer.

My recollection on the 1999 is the OBD power buss is through the CDM (or DDM as it’s also called ) so generally that won’t back feed to the ECU supply.

I would just 12 volt to the kidney fuse box bolt and a ground

It’s not trivial to remove the battery and keep 12 volt on the bus but it’s possible; I had to do it on Shagg once for inspection , to swap batteries

Hello Steve,

Thanks, but i am not sure what the kidney fuse box bolt is or where it is.

Before that advice i planned to bolt wires right to the lead connectors on the battery, and as i remove each one put a glove and rubber band around so neither terminal can touch anything while the battery is being removed and installed.
Did you see the bolts on my Volvo connectors for the battery? They are not the bolts you use to tighten the terminals to the battery, they are different bolts that stick up from the terminals. I used them to bolt wires from the solar panel directly to the battery terminals with only a fuse inline. I was thinking maybe that is what they are there for? They must be for something.
I'll post another pic of the battery terminals on this car.
I like your idea too though.

[MrAl]

Here is the pic of one of the studs on the battery terminals.
Easy to bolt wire right to those studs.

[abscate]

Pin 16 on the OBD should work for 12Vnto battery

Use pin 4 or 5 for ground