ECM-6300 and ECM-6B00 2000 V70R [BAD Battery to fusebox supply cable!] EPIC Troubleshooting Topic is solved

[abscate]

These control modules don’t ground things to ground but drain them through a transistor. That’s not the same as connecting them to a B- point. There could be other logic being triggered by the transistor so grounding could mess all that up.

[RickHaleParker]

What I don't understand is how a ground shorts to ground. If it was shorted to ground, shouldn't it be steady? Plus it's a pretty consistent pattern. That's the confusing part.

Ground side wire not Ground.

A circuit needs a switch to turn the circuit on and off. The switch can be on the high side or the ground side. In the case of the CDM ETM & CEL light the switch is on the ground side. The switch is in the TCM. It is a transistor that connects the ground side wire from the light to chassis ground. If the Ground side wire shorts to ground between the CDM and the TCM it will come on when it should not.

It could be leaking transistors in the TCM as Abscate pointed out.

Either way if the light is coming on when it should not be on. It is getting grounded when it should not be grounded.

[bmdubya1198]

Well, the CEL should in fact be on right now. When it's not on for another reason (other codes), then it doesn't turn on. This only happens when it's on. In this case, I have P0455 currently. If I clear the code, the CEL turns off and doesn't come back until the ECM cycles its tests again and detects the evap leak.

Activation makes sense though. Maybe the transistor in the ECM is just weak/malfunctioning? I still think it's an issue on the power side.

[bmdubya1198]

What leads me to believe this problem is on the cluster side is that it is affecting both the ETS light and the CEL. ETS goes to ECM B41 and CEL goes to B46. Two separate pins on the connector, two separate wires. The one common link between these two is CDM A18, which is the power source.

Of course, there is the possibility that the two wires are being grounded out somewhere. But through my troubleshooting thus far, I find it unlikely. Plus the way it's pulsing... there's a rhythm to it. It seems more like a failed transistor or something. Not a simply frayed wire.

Then again, the issue seems to be on the control side. The ECU seems to be grounding the circuit, then disconnecting it. But why would there still be the error code for the ETS light when that's not on at all? It flickers when it comes on momentarily while cranking, so the issue is present, but not obvious. I wonder if there is a link between these two controllers in the ECU. That could explain it, but beyond that I just don't know.
At this point, I'm still down to an issue either within the cluster or within the ECU. Shame you can't just swap around ECUs like M4.4.... the one drawback to ME7 cars.

[RickHaleParker]

Disconnect a lamp wire from the CDM and connect it to your test light. Connect the other end of the test light to a (+). If the test light behaves like the CDM light. The problem is external of the CDM.

[bmdubya1198]

Will try this today.

[bmdubya1198]

I unplugged 23/13D under the dash (the connector which holds both the CEL and ETS light signal wires) and touched the test light to the CEL pin on the ECU side of the connector. It indeed flashes just like the CEL when it's connected. ETS light didn't light it up, which is because the ETS light wasn't illuminated anyway. Just like when it IS connected, this only happens while the engine is running.

So it's definitely on the ECU side. I checked for continuity between the CEL and ETS wires, and they do not show continuity to each other or chassis ground. They only show continuity to ground when their respective lights are supposed to be illuminated, which should be normal.

Does anybody know exactly what controls the CEL and ETS light within the ECU? I believe that's the problem. Unless this is fairly easily repairable, I don't think it's anything to worry about. Once I get P0455 remedied this issue should go away, since the ECU will have no reason to illuminate either of these lights.

[abscate]

This is hard because I don't think the code in ME7 is public. Ive never seen it posted anywhere - for that matter I haven't seen 4.4 either. The tune guys may have decompiled it, but they won't share as that is their edge.

[bmdubya1198]

I haven't seen much info around. I'd tear open the ECU, but I'd rather find a spare to do that.

[RickHaleParker]

Wait a second. The CEl will flash if the ECM detects abnormal combustion.