2003 GMC Yukon grounding/electrical issue????

[wcter]

Hi everyone

I'm having a few issues with my 2003 GMC Yukon SLE, what I believe to be grounding issues, but I'm not certain on how to isolate said issue and don't have any diagrams either. Also I have more time to mess around than before anddddd this has been bugging me for a while so, hopefully I can get some help here.

But let's get straight to business!

Symptoms:
Right Rear Courtesy Light connector not giving power to bulb
Right Rear window switch only goes down, does not go up (left side works completely fine).
When rear windows are controlled from the driver switch, raising the windows is done in a stutter (this does not happen if controlled from the rear switch), as if the power is being cut and given every like .2 seconds. You can hear the motor click too.
Parasitic draw, battery dies after 4-5 days of being unused. Original owner installed a kill-switch to neglect repair.
Rear access open notification appears on cluster information center, even though it's not open. Haven't replaced the latch (sensor is built into the latch) yet as I'm unsure how I could test to see if it's a bad ground or faulty latch.
Hard start. FREQUENTLY taking 3 or more separate cranks to actually fire up. There's a P0343 code for the camshaft sensor which I suspect to be related.
Low coolant level text comes on cluster every once in a while during a drive then goes away seconds later (my temps are fine, and I have coolant)

What have I tried already?
Regarding the rear right light connector, I ripped out three different harnesses, none of them worked for the light. Also the harnesses I attempted to replace the original harness with did not have any window control unless from the drivers switch for some reason.
I have not tried a new switch for the rear right window not rolling up from that controller, but I can and will do soon (hopefully it's just that, lol).
Regarding the window stutter from the front controller to the rear windows, I have done absolutely nothing to resolve the issue as I think the issue is over my head and I'm too inexperienced to dig that one up.
I suspect the parasitic draw to be the aftermarket radio, but I have a multimeter and a bunch of free time. I'm gonna wake up tomorrow and pull fuses with a multimeter to locate the issue and go from there.
Hard start:
I've replaced the fuel pump and CAM sensor, the original owner replaced a couple fuel system components that I forgot of as well.

My MAIN concern is the hardstart.
I went to prom in this Yukon that needed to crank three times to start and I'm not really proud of it lmao

If you have any ideas about the hardstart or have diagrams that may help me track down any of the symptoms/issues above, PLEASE LET ME KNOW!!!! I'd much rather do this stuff myself then send it to a dealer only to be upcharged.

Have a great night.

 

[Fless]

Welcome to TYF, from the Centennial State! Sounds like you have some work ahead of you, but none of it is very difficult if you're handy. Post up some info about the history of the SUV: mileage, what kind of maintenance has been done, etc. There's a search function on this forum that is there for you to use, too.

Which engine (what's the 8th digit of the VIN)? Fuel pressure specs vary by engine type (flex fuel or not).

1. Crank-no-start, multiple cranks (assuming the crank speed is good): put a bidirectional scanner on it and see if you can do a CASE relearn. This syncs the cam sensor to the crank sensor, and that tells the PCM where the cam is in relation to the crank. Doing a CASE relearn is recommended anytime either sensor is replaced or changed; although it's not absolutely necessary, if successful that condition can be ruled out.

2. Verify fuel pressure: put a fuel pressure gauge (you can rent a kit at many auto parts stores) on the fuel rail (passenger side), turn the key on (engine off), and document the fuel pressure. Try cycling the key several times to see if the pressure builds a little. Here are the values you should be seeing, according to Haynes:

KOEO (key on, engine off)
Flex Fuel: 48-54 psi
Non-Flex: 55-62 psi
Easy enough to test without running the engine. If the pressure is in spec, turn the key off and see if it holds somewhat steady or drops like a rock.

3. Rear lighting: there's a junction block behind and above the RR tire, under the quarter panel. All of the rear lighting goes through that block, and it's a great place to check voltages and the quality of the connections.

4. Parasitic draw: you have a voltmeter; instead of pulling fuses, avoid waking up modules and use the test points on the mini fuses to find out what circuit has current floating. This doesn't work for the J-Case fuses, but you may find your draw on the smaller fuses. Measure the voltage drop across the fuse test points, and use the chart to convert to mA. Here's the chart for Mini Fuses: https://m.roadkillcustoms.com/wp-content/technical-pdf/Mini Fuse Voltage Drop Chart.pdf. Any fuse that has a voltage drop is carrying current.

If you have the AUTO HVAC head, note that it can take as much as 4 hours to fully sleep, so don't condemn it if it shows a draw, at least until you've given it time to snore.

Keep us posted on your progress. Many of us have dealt with one or more of these fault conditions.

 

[wcter]

Welcome to TYF, from the Centennial State! Sounds like you have some work ahead of you, but none of it is very difficult if you're handy. Post up some info about the history of the SUV: mileage, what kind of maintenance has been done, etc. There's a search function on this forum that is there for you to use, too.

Which engine (what's the 8th digit of the VIN)? Fuel pressure specs vary by engine type (flex fuel or not).

1. Crank-no-start, multiple cranks (assuming the crank speed is good): put a bidirectional scanner on it and see if you can do a CASE relearn. This syncs the cam sensor to the crank sensor, and that tells the PCM where the cam is in relation to the crank. Doing a CASE relearn is recommended anytime either sensor is replaced or changed; although it's not absolutely necessary, if successful that condition can be ruled out.

2. Verify fuel pressure: put a fuel pressure gauge (you can rent a kit at many auto parts stores) on the fuel rail (passenger side), turn the key on (engine off), and document the fuel pressure. Try cycling the key several times to see if the pressure builds a little. Here are the values you should be seeing, according to Haynes:

KOEO (key on, engine off)
Flex Fuel: 48-54 psi
Non-Flex: 55-62 psi
Easy enough to test without running the engine. If the pressure is in spec, turn the key off and see if it holds somewhat steady or drops like a rock.

3. Rear lighting: there's a junction block behind and above the RR tire, under the quarter panel. All of the rear lighting goes through that block, and it's a great place to check voltages and the quality of the connections.

4. Parasitic draw: you have a voltmeter; instead of pulling fuses, avoid waking up modules and use the test points on the mini fuses to find out what circuit has current floating. This doesn't work for the J-Case fuses, but you may find your draw on the smaller fuses. Measure the voltage drop across the fuse test points, and use the chart to convert to mA. Here's the chart for Mini Fuses: https://m.roadkillcustoms.com/wp-content/technical-pdf/Mini Fuse Voltage Drop Chart.pdf. Any fuse that has a voltage drop is carrying current.

If you have the AUTO HVAC head, note that it can take as much as 4 hours to fully sleep, so don't condemn it if it shows a draw, at least until you've given it time to snore.

Keep us posted on your progress. Many of us have dealt with one or more of these fault conditions.

I appreciate your response! I went ahead and pulled out the multimeter and found that my car was pulling .72 mA with the ECU sleeping - after pulling the DIC/IPC fuse, it dropped to about .30 mA of draw, so I believe I gotta pull out the cluster and trace the wires from there.

-

Kinda off-topic but I installed some LED interior lights all-around and they work great with the all-cabin lights on override, but when you select to have one light or two lights on with the overhead MAP button, they're significantly dimmer than they are with the override switch. Is there a ground ran to the a-pillar from the MAP overhead that might be corroded?

-

I found this video on chevrolet truck grounds (

), which is very similar to yukons, and have been following it. I havent fooled with the engine ground strap but I think I'll have to buy a new one as it's visibly corroded, but still attached.

I'll continue with a wire brush on all the grounds, replace the engine to firewall ground strap, and see if I'm still encountering the double crank issue.

I'll likely have to trace the ground from the driver window controls to remove the stutter (unless someone has a diag).
-

Also while I'm here, is there any way to test the rear latches to make sure the sensor built inside them is working? I'm assuming there is with a multimeter but I haven't been able to find anything online other than what someone said they did (vague and not very helpful) on another forum.

 

[Fless]

I think the decimal point is in the wrong place when you describe the draw. 0.72mA is less than 1mA. Do you mean 72mA (0.072A)? Or 0.72A? (that second one would be an issue, 720mA.)

Do you know if the cluster has ever been rebuilt with updated stepper motors for the gauges? LED backlighting? Not that either of those changes would necessarily cause a draw, just a question out of curiosity to figure out if it's ever been apart.

Clusters in these are known to cause parasitic draw when they get silver migration on the circuit board. In that case you'd need to disassemble it (YouTube has videos on this) and clean the circuit board with a soft toothbrush or the like, and some kind of 91% or rubbing alcohol. I've attached the pinout of the cluster connector.

A fully-asleep SUV should draw in the range of 15-40mA.

 

[wcter]

I think the decimal point is in the wrong place when you describe the draw. 0.72mA is less than 1mA. Do you mean 72mA (0.072A)? Or 0.72A? (that second one would be an issue, 720mA.)

Do you know if the cluster has ever been rebuilt with updated stepper motors for the gauges? LED backlighting? Not that either of those changes would necessarily cause a draw, just a question out of curiosity to figure out if it's ever been apart.

Clusters in these are known to cause parasitic draw when they get silver migration on the circuit board. In that case you'd need to disassemble it (YouTube has videos on this) and clean the circuit board with a soft toothbrush or the like, and some kind of 91% or rubbing alcohol. I've attached the pinout of the cluster connector.

A fully-asleep SUV should draw in the range of 15-40mA.

I'm new to using a multimeter and this stuff all around sorry for the confusion. I meant 72mA, yes.

I do know there's an aftermarket stereo, I know absolutely nothing about the cluster, though it seems pretty easy to take out and see if anythings been tapped into. So no, I got no clue if it's been rebuilt or if it's been apart unfortunately.

Thank you for the info!!! I'll take it apart soon and let you know if the draw drops.

 

[Fless]

Easy enough to remove the cluster, as well as to disassemble it. The trim panel around the cluster and the radio pulls out with just clips, but you'll need to drop the gear selector all the way down to "1" to wiggle it out.