Computer or Electrical Issue

More than likely you have a PCM failure. Take a look at the testing for the P1642 and it basically says that the module that sets this DTC is at faulty.

I would suggest checking one of the other codes and making sure it leads to the PCM as well.

I would suggest using one of the knock sensor codes.

https://www.2carpros.com/articles/how-a-knock-sensor-works

However, the fact that you have a circuit low code on both points to the PCM as well.

It is highly unlikely that you have two knock sensors that are shorted.

Let's run through this info and let us know what you find or what questions you have.

Thanks

Well, I tried a replacement PCM and it did not change anything. So I put the old one back in. I also have codes regarding the TCM connection and ABS CAN connection malfunctions. I really have no idea what is happening with this thing. Maybe it's the instrument cluster? I know the clusters on these store information rather than just the PCM, but no clue on where to go from here.

Only other thing is that the battery is constantly needing to be jumped off. With the car running 14amps will be pumped to the battery but it almost never starts by itself.

So changing the PCM resulted in the exact same codes?

Here is what I would suggest, put the new PCM in and start the vehicle even if you have to jump it and then scan for all the codes and let us know what they are.

If they are the exact same as above then you are correct that the PCM was not the issue even though that appears to be what it was.

If they are different but you still have the same issue of having to jump start the engine then the PCM was faulty but just wasn't causing the issue you are seeing.

Please let us know so we can be sure to be on the same page.

Thanks

For the record, I can't start the vehicle with the new ECM cause I can't program the VIN into it. It will just crank. But regardless, here are the codes with the new ECM:

P0455 (EVAP leak, gross leak)
P1000 (OBD readiness monitor not complete)
P1797 (CAN TCM/ECM Circuit Malfunction)
P1642 (CAN Link Circuit Malfunction)
P0332 (Knock Sensor 2 circuit low)

C1317 (?) Crankshaft position sensor circuit OR Fuel rail circuit?
B1712 (LF Door up switch short to ground)
C2000 (?)

Okay. That is good info.

When you say you can't program the VIN into it, do you have the capability to program the VIN but just cannot communicate with it to do this? Or does you scan tool not have the ability?

The fact that the new PCM has the CAN codes shows we have a communication issue and most likely a wiring issue. So the new ECM once program may fix this but with the knock sensor code I am thinking you may have an issue with the harness.

I do not have the capability to program. I have been looking at some software for my PC as I have a very good USB/OBD2 dongle I use with Forscan.

I did notice the same knock sensor code. Do you suggest to follow these two wires back to the harness? There's barely any room in this engine bay.

Correct. You have the same circuit codes but some of the others are gone. So you don't have to program the PCM for it to start monitoring all these circuits. So that tells you that the PCM had issues but the 3 circuit/CAN codes are your issue.

So the next step is to get a scan tool that can program this PCM even if you just borrow one from a friend. Because if you can program this and it starts and runs properly then these codes are not an issue or at least not causing the issue you are seeing with what started this post.

What I suspect is happening is there was an issue with the PCM causing the reduced power and if these communication codes prevent the PCM from being programmed then that is a different issue. However, we need to fix that to fix the first issue.

So if it were me, I would track down a scan tool before I start tracing wires because we don't know if this is preventing the programming of the PCM yet.

Well, even with the new PCM installed it still will give me the "engine failsafe mode" message after about 30 seconds or so. Which I think is automatic when one of these CAN codes shows up.

Okay. If you are getting that message with out even starting the engine then you have a circuit issue.

I would go no further then the P1642, I attached the info below for it, where it states the CAN circuit is shorted or the control module is the issue. Due to the other PCM faults that would be the module effected but clearly that doesn't appear to be the issue.

Plus this code is the one causing the limited power as it states below.

What I would do is check the voltage at the DLC on pin 6 and ground. Then 14 and ground.

https://www.2carpros.com/articles/how-to-check-wiring

Let's see what the voltage is on both of these and start working through it. I suspect they are going to be wrong but we need to start at the beginning.

It says the DLC connector under driver side fuse box. Well, there is no fuse box on the driver's side. Except under the hood, and there is no connector there. Does it mean the OBD connector? If so, how are the terminals numbered? Also I attached a picture. It doesn't look too good. And also when I replaced the transmission range sensor the connector looked like this too.

As for the voltages, #14 to both grounds read at 1.84 Volts at both pins. #6 to both grounds fluctuated between 0-2.4volts.

Oh man. That is an issue. It may not be the issue but that is the connector that we need to check those voltages and that is definitely an issue.

So these voltages need to add up to 5 volts. That is the way these modules communicate is the messages are coded based on the varying voltage. However, if one is 2.8 volts then the other is 2.2 volts.

They should not drop lower then 2 volts on the low side (pin 14) or higher then 3 volts on the high side (pin 6).

The fact that you have the low side at 1.84 volts shows it is being pulled to ground and the high side is the same thing. It should not be dropping to 0.

The fact that you have corrosion on this connector is where we need to start because if these pins are shorted to ground due to that corrosion then that is going to be the issue.

However, even if it is not the issue, it is something that will cause issues when you are trying to use the DLC.

Was this vehicle in a flood? I am not sure I have ever seen a DLC that corroded.

I replaced the connector. Now I am getting 1.84 volts at pin 14 and 3.02 volts at pin 6. I don't think this is any better. Ha

Unfortunately not. The next step is to continue monitoring this voltage (easier if you have two meters) and start unhooking modules that is on this network and see when the voltage returns to 2.3 volts and 2.7 volts.

When it does, you just disconnected the issue. It is either the connector, wiring, or module.

The fact that you already found corrosion that, means we need to be looking for that in these connectors as well.

I would start with the ECM. See the wiring diagram below for all these modules.

The two wires you had me check go straight to the instrument pack, according to this. How do I remove that to check? I have a hunch about it being such a short distance from this dlc connector.

Correct. That is the cluster. I attached the info on that. Basically they treat this as a gateway or pass through module.

So they use this to access all the other modules from the DLC.

The only issue you are going to have, is you will have to access the voltage of this network from another source because you will lose your connection once this is out.

The voltage on this network is going to be the same anywhere you check. So if you disconnect the cluster then just check the voltage on the network to all their all modules. Not the wiring to the DLC. Looks like 13 and 14 are the pins to the rest of the network.

If the voltage returns normal on these wires then the cluster is the issue.

13 goes to the white wire at the ECM, but it says only one white and one blue wire, looking at it on the car the only setup where this exists is the fan that cools off the ECM. I get 12 volts whether or not the instrument cluster is plugged in or not.

Okay. Those two wires, white and blue that go the ECM from the DLC are not part of this CAN system.

So just to be sure I was clear, you want to measure the voltage on any of the wires on that diagram that are labeled CAN data + or -.

So as you are unhooking these modules we need to know what the voltage is on these two wires. They are going to be the same no matter where you check it in the system as they are all spliced together onto the same circuits so we just need to know when they return to 2.3 and 2.7 volts (or close to it).

Just to be clear. These voltages should be read with the ignition on, or the car running, or just static?

Great question. Just key on engine off is fine as that gets the bus awake and communicating.

Let me know what other questions you have as you work through it. Thanks