Out of storage and won’t start… ideas?

[MisterDave]

Are those codes permanent, historical, current or pending? Or more importantly, which are current/pending?

I would screen shot the screen or take a picture and post. Then clear and see what comes back.

I didn’t have a lot of time to work on anything lately. I just wanted to get the codes. I should have some time tomorrow to try your suggestion.
I appreciate the advice.
thank you

 

[MisterDave]

I’ve cleared the codes and tried to start again(same result) and then scanned for codes again….
Here’s the list:
PSCM - Power Steering Control Module
U2105-00 ; Lost Communication With Engine Control Module
C0845-01 ; Control Module Ignition 1 On And Start Circuit - Short To Battery
BCM - Body Control Module
U2105-00 ; Lost Communication With Engine Control Module
U2113-00 ; Lost Communication With Inflatable Restraint Sensing And Diagnostic Module
U2125-00 ; Lost Communication With Telematic Unit
U2172-00 ; Lost Communication With Digital Radio Receiver Control Module
IPC - Instrument Panel Cluster
U2113-00 ; Lost Communication With Inflatable Restraint Sensing And Diagnostic Module

 

[Gtstorey]

Again, need to know what the status of those codes are. History (shouldn't be since they were cleared), permanent (I don't think any of these would set a permanent code), Pending or Current.

You can ignore any of the codes for modules that don't exist, U2113-00, U2172. I'm not sure about U2125 since I don't remember anything called "Telematic Unit".

The if the others are current, then they would likely cause a no start condition. Let's start with this test for the lost communication.

"To test the termination resistors, simply place the Ohmmeter leads across DLC terminals 6 & 14 with the key OFF.  The Ohmmeter should read 60 Ohms if both resistors are OK (they are in parallel, so the total resistance is less than either resistor by itself).  So if your Ohmmeter reads 120 Ohms, you have one open resistor.  If your Ohmmeter reads infinity Ohms, you may have 2 open resistors, but it’s much more likely that you don’t have a good connection at the DLC.  If your Ohmmeter reads 0 Ohms, the GMLAN +/- circuits are shorted together."

From https://resources.aeswave.com/ATG-05_Network-Diagnostics-and-Module-Programming.pdf

You will have to find the pinout for the DLC, it's been posted on here many times and is standard for all OBD2 vehicles.

I'll have to look up the C0845-01 code in the service manual to see the exact details this evening.

 

[MisterDave]

Again, need to know what the status of those codes are. History (shouldn't be since they were cleared), permanent (I don't think any of these would set a permanent code), Pending or Current.

You can ignore any of the codes for modules that don't exist, U2113-00, U2172. I'm not sure about U2125 since I don't remember anything called "Telematic Unit".

The if the others are current, then they would likely cause a no start condition. Let's start with this test for the lost communication.

"To test the termination resistors, simply place the Ohmmeter leads across DLC terminals 6 & 14 with the key OFF.  The Ohmmeter should read 60 Ohms if both resistors are OK (they are in parallel, so the total resistance is less than either resistor by itself).  So if your Ohmmeter reads 120 Ohms, you have one open resistor.  If your Ohmmeter reads infinity Ohms, you may have 2 open resistors, but it’s much more likely that you don’t have a good connection at the DLC.  If your Ohmmeter reads 0 Ohms, the GMLAN +/- circuits are shorted together."

From https://resources.aeswave.com/ATG-05_Network-Diagnostics-and-Module-Programming.pdf

You will have to find the pinout for the DLC, it's been posted on here many times and is standard for all OBD2 vehicles.

I'll have to look up the C0845-01 code in the service manual to see the exact details this evening.

All of the codes say History|Current except for the code “C0845-01 ; Control Module Ignition 1 On And Start Circuit - Short To Battery” which just says History.

 

[Gtstorey]

Let's ignore C0845 for now then, although it may still be an issue since it should clear with the reset.

Do the resistance test and I'll check the service manual for the actual details on the U2105. But the ECM doesn't appear to be communicating. Either it isn't getting power, or the data wires aren't right.

 

[Robinjo]

I still haven't seen where the grounds were cleaned, checked and confirmed. Mine did something similar to this once and it was the ground under/around the fuse block. Cobalt vehicles seem super sensitive to grounding issues.

 

[Gtstorey]

If the high speed data wires check out, then we can start looking at why the ECM isn’t communicating. It’s probably a lack of power to it, and that might be a ground problem. Greater than 50% chance it is.

 

[MisterDave]

I still haven't seen where the grounds were cleaned, checked and confirmed. Mine did something similar to this once and it was the ground under/around the fuse block. Cobalt vehicles seem super sensitive to grounding issues.

I did check the ground under the fuse box and it didn’t look bad. I sanded the contacts any way and re assembled. I didn’t do that to all of the ground points in the car, but I did check ground continuity.

 

[MisterDave]

Again, need to know what the status of those codes are. History (shouldn't be since they were cleared), permanent (I don't think any of these would set a permanent code), Pending or Current.

You can ignore any of the codes for modules that don't exist, U2113-00, U2172. I'm not sure about U2125 since I don't remember anything called "Telematic Unit".

The if the others are current, then they would likely cause a no start condition. Let's start with this test for the lost communication.

"To test the termination resistors, simply place the Ohmmeter leads across DLC terminals 6 & 14 with the key OFF.  The Ohmmeter should read 60 Ohms if both resistors are OK (they are in parallel, so the total resistance is less than either resistor by itself).  So if your Ohmmeter reads 120 Ohms, you have one open resistor.  If your Ohmmeter reads infinity Ohms, you may have 2 open resistors, but it’s much more likely that you don’t have a good connection at the DLC.  If your Ohmmeter reads 0 Ohms, the GMLAN +/- circuits are shorted together."

From https://resources.aeswave.com/ATG-05_Network-Diagnostics-and-Module-Programming.pdf

You will have to find the pinout for the DLC, it's been posted on here many times and is standard for all OBD2 vehicles.

I'll have to look up the C0845-01 code in the service manual to see the exact details this evening.

I get 60 between pin 6 &14

 

[Gtstorey]

Next step will be to check power to the ECM. We can start with a voltage drop test until I can post the wiring diagrams for the ecm. Temporarily run a piece of wire firmly attached to your negative terminal of your battery to the fuse box area and check for voltage between the ground wires at the stud under the fuse box and the temp wire. With the key in the run position. You should have less than 1 volt showing. Also confirm voltage at the B+ terminal is the same at the temp wire and the ground stud.

 

[MisterDave]

Next step will be to check power to the ECM. We can start with a voltage drop test until I can post the wiring diagrams for the ecm. Temporarily run a piece of wire firmly attached to your negative terminal of your battery to the fuse box area and check for voltage between the ground wires at the stud under the fuse box and the temp wire. With the key in the run position. You should have less than 1 volt showing. Also confirm voltage at the B+ terminal is the same at the temp wire and the ground stud.

I haven’t had a chance to run a wire from the battery negative to the back. My garage is still in boxes
But I try connecting from the ground under the fuse box and the positive at the fuse box and there wasn’t a change when I put it in run. It was ready 12.3 or 12.2.

 

[Gtstorey]

Ground is probably ok but not 100% certain. What was the battery voltage when you check it like that?

Have you checked every fuse? Especially any that are ignition or run/start or ECM labeled.

I didn't get a chance to review the service manual for your particular codes. Maybe tonight.

 

[MisterDave]

Ground is probably ok but not 100% certain. What was the battery voltage when you check it like that?

Have you checked every fuse? Especially any that are ignition or run/start or ECM labeled.

I didn't get a chance to review the service manual for your particular codes. Maybe tonight.

Ground is probably ok but not 100% certain. What was the battery voltage when you check it like that?

Have you checked every fuse? Especially any that are ignition or run/start or ECM labeled.

I didn't get a chance to review the service manual for your particular codes. Maybe tonight.

The battery voltage stayed the same…. Did you want me to check at the battery again too and compare the two locations?
To be sure I went through and checked every fuse in both fuse boxes. All are good.

I had another suggestion to check under the fuse box for any corrosion or loose plugs…. I took that all apart and it all looked good.

I was thinking of renting a relay tester if I can find one. Maybe it’s a relay?

 

[Gtstorey]

Yes need to confirm battery voltage is pretty close to the same as what is measured at the back of the car. 12.2 at the back of the car with a fully charged battery at 12.6-12.7 would indicate you have some connections that aren't great. 12.2 at a fully charged battery would indicate a bad battery.

But neither is bad enough that the ECM wouldn't wake up. At some point you are likely going to have to check for power at the ecm. No need to get a relay tester. If you want to get something that will be useful, Get some backprobe connectors (How to backprobe an electrical connector Ricks Free Auto Repair Advice | Car Repair Tips and How-To Advice ) for you DVM so that you can check connections with everything hooked up.

And don't get distracted with a lot of random try this stuff. The secret with doing electrical is starting at one point and methodically going up the chain. I still haven't had a chance to dig into diagnostic codes. I'll try to do some looking this evening and post at least the wiring diagrams.

A random though just occurred to me. Does your code reader give you the option to read individual modules? Since you didn't list any from the ECM and it looks like the other modules aren't finding it is why I'm assuming it isn't "awake". If you have the capability, see if you can read the ECM/PCM only, or connect to it for live data. What scanner did you get?

 

[Sluggonaut]

I haven’t had a chance to run a wire from the battery negative to the back. My garage is still in boxes
But I try connecting from the ground under the fuse box and the positive at the fuse box and there wasn’t a change when I put it in run. It was ready 12.3 or 12.2.

12.2 at a fully charged battery would indicate a bad battery.

When my donor battery finally bit the dust earlier this year, it was reading 12.4 fully charged. The new one was over 13, so my experience aligns with Gtstorey's comment.

 

[Gtstorey]

When my donor battery finally bit the dust earlier this year, it was reading 12.4 fully charged. The new one was over 13, so my experience aligns with Gtstorey's comment.

You have to be careful with the reading immediately after charging a battery also. It will read higher than normal for a short period of time. Over 13v is concerning as an at rest voltage. But I think AGM batteries will read a little higher than a lead acid battery.

 

[Sluggonaut]

You have to be careful with the reading immediately after charging a battery also. It will read higher than normal for a short period of time. Over 13v is concerning as an at rest voltage. But I think AGM batteries will read a little higher than a lead acid battery.

I think that was the reading with the charger on the batteries.

 

[Gtstorey]

And with a charger it would typically read closer to 14v, but it may have been in a maintain or float mode. But at that point you are reading the voltage of the charger not the battery anyway.

 

[Sluggonaut]

And with a charger it would typically read closer to 14v, but it may have been in a maintain or float mode. But at that point you are reading the voltage of the charger not the battery anyway.

I had my trickle charger plugged into its remote port during my battery swap process and I was testing on the battery posts. If it was reading just the charger's voltage, why would the bad and good battery return different readings?

 

[Gtstorey]

I guess that it can depend on the charger. But the voltage of the charger always has to be higher than the battery to actually charge. Maybe some of the smart chargers reduce the voltage on depleted batteries to a lower level to keep the temperature down.

Or if there is a shorted cell in the battery it might pull the charger down, especially a trickle charger. And this may hold true for a severely depleted battery on a trickle charger.