V1 MIL Light on After Clearing Codes

[Robinjo]

I installed PH Tuners, downloaded my files and removed all the Bank 2 O2 Sensor code along with the codes being thrown for the nonexistent Evap System. Also, I removed via HP Tuners was a P0650 MIL Malfunction Code, which GTStory noted was odd. Cleared all the codes using my Bluetooth scanner and went for a dive. The MIL (Check Engine) light did not go away. When I got back home I scanned for stored and pending codes there were still not any.

So, this makes me believe the P0650 was valid. Any ideas where to start looking?

 

[Gtstorey]

There is a chance that the MIL light is being caused by the one of the remaining modules. I think there are a few things that trip the MIL that are outside the ECM/PCM.

Otherwise you are checking voltages all the way to were the MIL light signal originates. I think the ECM sends a signal to the BCM saying that the MIL light needs to be turned on and the circuit is controlled by the BCM. This is all from memory so it might not be correct or is different from the older models. It could be the other models telling the ECM to turn it on. But do remember reading that it's not a straight forward as ECM seeing a problem and telling the MIL to cut on.

You really are going to have to track down the MIL light circuit in the wiring diagrams.

 

[Robinjo]

Ooof. This sounds like it's going to be really difficult.

 

[Gtstorey]

Not necessarily. Start with finding the wiring diagram for the MIL light on Alldata. I think it is likely with the Instrument cluster wiring.

 

[Robinjo]

I'll give it a go. This Goblin sure wants me to learn wiring schematics......

 

[Gtstorey]

Newer models are controlled by the ECM by grounding the circuit. So you either have a short to ground of that circuit or the MIL illumination is correct and you have another module causing the light. Disconnect ECM connector and see if it is still lit.

 

[Robinjo]

Disconnect ECM connector and see if it is still lit.

Just for clarity, when I disconnect the ECM connector I just turn the engine to 'run' and not to try firing with this disconnected?

 

[Robinjo]

Brown/White wire for the MIL to circuit 419 goes to Engine Control Schematic. Engine Control Schematic calls out C1 40 (edit -found it) and C201 C8? I'm a little stuck here right now, I'm not sure where the diagram is taking me next. I'm still searching though.....

Found C1 40.....

 

[Robinjo]

Adding this diagram so I have it later for testing.

MIL Always On Testing Sequence:

 

[Desert Sasqwatch]

C201 looks like the connection between the engine harness (PCM) through the chassis harness that feeds to the instrument cluster. The C1 is the connection at the PCM, the pin 6 is on the instrument cluster - if I'm reading this correctly. The logic in the instrument cluster will provide a DC voltage (12V?) and the PCM will provide a ground to illuminate the MIL. If there is a short to ground anywhere on the circuit from pin 6 on the instrument cluster to the PCM, the MIL will illuminate - as long as the logic in the instrument cluster is providing a DC voltage. I doubt there is a short in the instrument cluster, so there has to be a wiring issue - OR - the PCM is detecting a fault that is (correctly) providing the ground.

 

[Ross]

The instrument panel to body harness.

 

[Robinjo]

But that connector went away during the thinning and combining, right? I just want to make sure my thinking is correct.

 

[Gtstorey]

I'm wonder if the "Logic" supplying ignition voltage is actually real (although the newer model diagrams also show it). If there is actually Logic controlling it, it must pretty much be "Ignition is on - supply voltage".

 

[Gtstorey]

But that connector went away during the thinning and combining, right? I just want to make sure my thinking is correct.

I think it did go away. I'm thinking maybe you ended up grounding that wire when you eliminated that connection.

 

[Robinjo]

So really what I'm looking for is continuity between the IPC (#6) and the C1 ECM (#40) connectors, correct? If I do not have it, I know where the issue is. If I do have continuity, then I need to keep investigating further.

 

[Desert Sasqwatch]

And check that connection between IPC #6 and C1 #40 for any connection to ground - with the PCM connected and disconnected.

 

[Gtstorey]

So really what I'm looking for is continuity between the IPC (#6) and the C1 ECM (#40) connectors, correct? If I do not have it, I know where the issue is. If I do have continuity, then I need to keep investigating further.

Actually you are only looking for ground between those points. Either it's seeing ground in the wiring or it's seeing it through the PC, but it has to be seeing ground after the MIL light. It can have continuity between the ends and still see ground.

 

[Desert Sasqwatch]

If the C1 #40 is disconnected (which should be the only place that ground will be possibly present) and there is continuity on the circuit to ground, then there is a short in the connection/wiring between IPC #6 and the connector C1 to ground that needs to be found and fixed.

 

[Gtstorey]

Why are you not following the diagnostics steps you posted? With the exception of getting to the point of replacing the PCM. If you get to that point we need to confirm that you aren't getting a real code from another module. I can do that with my tech2 clone.

 

[Robinjo]

Why are you not following the diagnostics steps you posted?

I just found it today. I'm planning to work on this over my Christmas break from work. I thought possibly I could just jump to checking continuity as that is really easy to do.