5.3 starter issue, and parasitic battery drain.

[xDan]

So I've got a 2003 4x4 with a 5.3. lately I've had some battery drain problems. I connected my multimeter to test amperage draw. I turned on the interior light door disable switch but when either front door is opened or closed, for 20 seconds it will show 270 to 450 mA draw, then drops to a range of draw between 20mA (good) to 150mA. I've pulled about 30 different fuses, nothing has changed.

After putting all the fuses back in, the battery was charged but then the engine wouldn't turn over. Starter solenoid engages and I can hear the gear engage but no power to turn the engine over. I bought a new battery, had to charge it up because it was only 70%, same issue with starting as the old (6 years old) battery.

I decided to look at the starter and it's terminals. Terminals were pretty clean and dry but the solenoid and starter body were very oily and had caked on dirt so I decided to pull the starter. What a PITA that was, access to the electrical cables on the 4wd models requires removing the right wheel, ABS sensor wire plug, solenoid shield, the bloody oil dipstick tube!..and an air ratchet, because nothing else fits between the frame and inner wheel well. LOL. I got the starter degreased and cleaned up, I'll find out tomorrow if the SUV starts up or not.

If anyone has suggestions or experience tracking down odd parasitic draws on these things, I'm all ears.

 

[Fless]

I would recommend using the DVOM method instead of pulling fuses, since you don't want to be waking up modules when fuses are reinserted. Each standard fuse has two test points on it, and the fuse is left in place as the voltage drop is measured. Once the mV drop is measured, there are conversion charts online to convert to the mA draw value. If you need those charts and can't find them, say so and I'll post a link.

EDIT:
Here is where you can find the Voltage Drop Charts for multiple styles of fuses. Be sure to use the chart that matches the fuse package.
https://www.powerprobe-emea.com/ES/knowledge/fuse-voltage-drop-charts/

Here's a good video (and there are many others) about testing for parasitic draw:

EDIT: any aftermarket alarm or other device installed?

Some common sources of parasitic draw on these are (not in any particular order):
1. OE radio
2. Dash cluster (search for Chevy cluster silver migration)
3. Water in one of the PCM connectors
4. Driver's door latch

If you have the auto HVAC head, it can draw 60mA or so for 4 hours or more until it goes to sleep. Obviously there could be other sources, so let us know what you're finding after you get it running, and as your testing moves along.

 

[OR VietVet]

Check by pulling relays, too.

 

[xDan]

Well.. I cleaned the starter and tested it, gear pops out and spins up, teeth in good shape. I inspected and tested the power cable to the starter, no connection to ground and has 0.5 ohms resistance to the battery. Battery terminals are also just fine. I pulled the fuses to the xenon headlights and the trailer power but with no ignition, just connecting a new, fully charged battery I'm now getting voltage across the battery drawing down to 10.8V, I connected my 100 amp jumper cables to a running vehicle and on cranking, I can hear the starter gear hitting the ring gear but that's all it does. Gauges aren't getting enough voltage to work properly either. For electrical testing I've got a DVM and tech 2.. Can't do the dvom method on the large fuses, there isn't access holes and I can't do that for long because the battery drain is so high now.

 

[rockola1971]

If im understanding your post correctly you are now working with a new fully charged battery (which new doesnt mean a good battery) and you are reading 10.8v across the battery while the starter is engaged? That is about what a starter that is cranking down to (10.8v). While parasitic draw is a common problem on C and K chassis. A problem that can happen even when the starter is NOT being cranked is the solenoid which is just a high current rated switch/relay contact could have its contacts bridged with conductive material from the contacts. This is caused by wear and tear by arcing as the contacts just close and just open up. This conductive material doesnt provide enough current flow to spin the starter over but is enough to give your starter some power which it will gladly take as a load and run the battery down. The solenoid could be junk.

The ground between engine block and firewall is a common one to break or corrode and cause the BCM to act a fool and not goto sleep which drains the battery down.

 

[OR VietVet]

Starter and solenoid assembly.

 

[xDan]

If im understanding your post correctly you are now working with a new fully charged battery (which new doesnt mean a good battery) and you are reading 10.8v across the battery while the starter is engaged? That is about what a starter that is cranking down to (10.8v).

Without the key even in the ignition, voltage is dropping as if something like the starter is loading it. Because I don't have that inverted torx for the solenoid removal, I brought the starter to a local shop this morning. The ground to the engine block looks solid if a little oily. I'll give that a clean and reinstall.

 

[xDan]

I left the battery disconnected after a full 10 amp recharge over night, if it's voltage is below 12.85, I'm returning it.

 

[rockola1971]

Without the key even in the ignition, voltage is dropping as if something like the starter is loading it. Because I don't have that inverted torx for the solenoid removal, I brought the starter to a local shop this morning. The ground to the engine block looks solid if a little oily. I'll give that a clean and reinstall.

And if the solenoid is bridged by carbon material from arcing it could very be draining the battery down. There could also be an internal shorted cell draining the battery down. Battery charged overnight should read around 12.86v +. If it dont then the battery is bad. (after checking output voltage of charger).

 

[xDan]

The battery left for two days settles in at 12.7V. it's probably fine. The one I removed drops to 12.5V after a day... Probably on its way out.

I had the starter solenoid replaced by a starter and alternator shop, but the original didn't have a problem engaging the starter motor contacts and the motor only had some minor surface rust on the inside of the housing and on the stator which the shop cleaned up. The brushes are in great shape. I checked for a seized engine but it turns easily enough.

Switching to acc, with IGN A 40A and IGN B 40A in, battery voltage drops from 12.45V to 12.25V.

Switching to run, it drops to 8.75V then increases to 9.6V.

Pulling IGN B 40A: drops to 10V on acc and run.

Pulling IGN A 40A: drops to 10.5V on acc, and 8.75V on run.

This initial voltage drop recovers over time when the key is left in run. If I put it in run then attempt to crank, the starter solenoid engages but there isn't power to crank the engine.

With the key left in run position and low headlamp relay removed as well as front, both rear marker and brake light fuses removed, (to prevent exterior lights from drawing power when ignition power drops) with main ign fuses back in, it's voltage drop across fuses are the following:

PCM: 0.001 15A fuse
0.218A
SIR: 0.045 15A fuse
9.83A
TBC IGN 1: 0.050 10A fuse
6.74A
RADIO: 0.003 15A fuse
0.655A
INFO: 0.003 15A fuse
0.655A
RADIO AMP: 0.005 30A fuse
2.70A
SBA: 0.040 15A fuse
8.73A
O2B: 0.060 15A fuse
13.10A
O2A: 0.053 15A fuse
11.57A Improper voltage probe technique makes all this bad data.