Well it's great that your enjoying your H2 and sorry to hear about your fluke meter, when you do get another one remember to use the 10amp range, better still use the 1 Ohm 10Watt resistor.

I see hummerz has just updated you with details on the batteries, basically 11.88V is not so good. Lead acid batteries do not like being held at low voltages, it reduces their life and will invalidate any warranty.

Just to mention again your figure of 0.15mA (because we care) this value is 0.00015amps as mA are 1/1000th of an amp, the normal draw of a Hummer is around 0.030amps, so your figure is 200 times too small, it's really, really tiny, impossible I'd say.

Put it this way, suppose your H2 is worth $30000 and I gave you $150 for it, you wouldn't be too happy would you?

You probably don't need to buy a new meter, just fix your old one. As the volts and resistance ranges still work you're probably thinking its ok, however inside there are 2 fuses which protect the meter on current measurement ranges, one is for the 10A range, the other for the 200mA range. The 200mA fuse will be burnt out, so just replace it with one of the same value, however the 10amp range is most probably still working.

Remember a new 200mA range fuse will blow the instant you connect the meter in circuit, even the 10A range is risky in my opinion.

To prove this I repeated the exact same exercise with an old meter and yes the 100mA fuse blew instantly !!!


Following the advice from members like hummerz finall MixManSC will save you time and money and will help you enjoy your H2 to the full.

I've got $150 dollars here waiting

 

Update on battery situation. My multimeter was showing the volts at 11.83. Advance auto parts had the reading at 11.95. Was asked if I wanted battery charged would take 30 min I said yes…30 min later the battery was leaking extensively in the machine. They gave me a refund on the battery. They didnt have any bigger batteries for H2. Ordered a Odyssey Extreme. Will have it on Friday. Also have another fluke multi meter coming in. Only really issues left, battery, possible parasitic drain, exhaust needs replaced (will do in spring) engine coolant leak ordered ac delco seal tabs. Interior and exterior are super clean. Will get some photos of the progress. Very very close to turning this around. Thx again everyone for tips and feedback.

 

Cleaned up Hummer logo

Doors cleaned/buffed vs uncleaned cargo rear.

Front complete

 

Dont know where you are located but I have most of the factory exhaust from the cats back which has a Flowmaster 50 series muffler on it. I'm in West Columbia, SC....

 

Vax1op369 look at this oscilloscope trace.

This is a plot of the inrush current flow through a 1ohm resistor when first connected, notice it peaks over 8 Amps.

From this the Hummer's load resistance can be roughly estimated which is 4V/8Amps = 0.5 ohms (in this case!)

A multimeter typically has a very low resistance, so connecting it in circuit the inrush current will be 12V/0.5R = 24Amps !!! (very roughly speaking)

With a new battery, freshly charged the inrush current is likely to be very much higher!


(the above plot was made today)

Your Fluke's mA range fuse will most certainly blow, it's10A range fuse might survive, but very doubtful and it could be risky.

To overcome this measurement problem, GM devised a procedure using a special tool called a "J 38758 Parasitic Draw Test Switch" like this one on ebay (expensive)



Briefly the clamp connects in line, a 10 Amp meter is connected across it, then the switch is turned-off, this ensures that the inrush is eliminated thus protecting the meter.

This is the full GM Parasitic Load Test procedure:-

1. Disconnect the battery negative cable from the battery negative terminal.
2. Install the male end of the J 38758 to the battery ground terminal.
3. Turn the J 38758 **** to the OFF position.
4. Install the battery negative cable to the female end of the J 38758 .
5. Turn the J 38758 **** to the ON position.
6. Road test the vehicle and activate ALL of the accessories, including the radio and air conditioning. This may take up to 30 minutes.
7. Park the vehicle. Turn the ignition switch to the OFF position and remove the ignition switch key.
8. Connect a 10-amp fused jumper wire to the test switch tool terminals.
9. Turn the J 38758 **** to the OFF position. The current now flows through the jumper wire.
10. Wait 1 minute. If the fuse blows, install an inductive ammeter and locate the current draw.
11. Turn the test switch ON, and then remove the fused jumper wire.
12. Set a digital multimeter to the 10A scale.
13. Connect the digital multimeter to the test switch tool terminals.
14. Turn the J 38758 **** to the OFF position. The current flows now through the digital multimeter.
15. Wait 1 minute. Check and record the current reading.

15.1. When there is a current reading of 2A or less, turn the J 38758 **** to the ON position. The electrical current will now pass through the switch.
15.2. Then switch the digital multimeter down to the 2A scale for a more accurate reading when the J 38758 **** is turned OFF.
16. Turn the J 38758 **** to the OFF position. Wait 15 minutes for most vehicles.
17. Check and record the current reading.
18. Note the battery reserve capacity, amp hour rating. Refer to Battery Usage .
18.1. Divide the reserve capacity by 4, amp hour rating by 2.4.
18.2. Compare this to the multimeter milliampere reading taken in the previous step. The parasitic current drain should not exceed this number. Example: If a battery has a reserve capacity of 100 minutes, (60 A/H) the current drain should not exceed 25 mA.
19. If excessive current drain is not found at this time and there are no other apparent causes, complete the following:
20. Using the MIN/MAX function of the digital multimeter, monitor the parasitic drain overnight or during the day. This will determine if something has been activated during that time frame.
Notice: The test switch must be in the ON position when removing the fuses in order to maintain continuity in the electrical system. This avoids damaging the digital multimeter due to accidental overloading, such as a door being opened to change a fuse.


Important: Removing fuses, relays, and connectors to determine the failure area may wake up modules. You must wait for these modules to go to sleep or use the sleep function on the scan tool.
21. When the vehicle has an unacceptable amount of parasitic current drain, remove each fuse one at a time until the current drain falls to an acceptable level. This will indicate which circuit is causing the drain. Refer to Power Distribution Schematics in Wiring Systems to diagnose exactly which part of the suspect circuit is causing the parasitic drain. In some cases a non-fused circuit or component, such as a relay, is the cause of excessive parasitic current drain.
22. Repeat the parasitic current drain test procedure after any repair has been completed to make sure that the parasitic current drain is at an acceptable level.
23. When the cause of the excessive current drain has been located and repaired, remove the J 38758 .
24. Connect the battery negative cable to the battery negative terminal.
GM put a lot of work into this test procedure and for good reason too, notice they did everything to protect the meter and did not advise just connecting it in circuit.

Something tells me you're going hook your fluke up anyway, in which case the fuse(s) will most likely blow (quickly and silently hopefully) and once again you'll be reading values that are meaningless.
There is no easy of telling a meter has blown fuses other than removing and checking them, the meter will still measure everything (except current) so you can use it on ohms to check the fuses (which must be removed)

Anyway I tried to my best to guide you and I sincerely hope you find the problem, either way keep us posted.

 

Appreciate the post, will certainly get in touch.

 

Thank you once again for the detailed write up. I purchased the 1 ohm to 10 resistor. Picked up wires for it too. Also have purchased fuses to replace the blown fuse. Friday afternoon will be testing and getting everything together. Everything makes much more since now on the multimeter the amperage, cords, how to use the meter…Have walked into unknown territory and really do appreciate the assistance. Will test with both devices. Ill also make sure to pass this information learned onto other Hummer enthusiasts in the future. Plan on making a youtube channel explaining all the crazy amount of info have learned. Chat soon!

 

“To overcome this measurement problem, GM devised a procedure using a special tool called a "J 38758 Parasitic Draw Test Switch" like this one on ebay (expensive)”



Is this a scam?

This looks just like a battery cable connected to an inline battery disconnect switch sold in any auto parts store. Is there more to it than is visible in the photo? These rotary **** disconnects are commonly used on collector cars in storage to eliminate………guess what……parasitic draws.

 

that is what it looked like to me too. a pigtail adapter from GM side post to top post to a cutoff then back to GM side post? i guess it leaves clearance for an amp clamp in a tight battery situation like hidden in a wheel well or under a seat or cowl.

 

This a legitimate GM gizmo - a switch on a wire..