Aftermarket stereos installed in these can really create havoc if not done properly. Simply pulling a fuse probably won't be enough to find out. The only way to know how it was installed, is going to be pulling it out and checking the wiring job yourself. And you want to completely disconnect it and see if the symptoms disappear.

The OEM stereo is tied into the body control module, and is treated by the system literally just like any other module on the vehicle. Splice a new stereo into the wrong wire and who knows what will happen electronically. I do know my Tech 2, while scanning for codes, also checks the OEM stereo and amplifier. It seems logical to me that in an aftermarket install, that should be programmed out with a custom tune. So I live with my OEM stereo that works great still, but has a few faded buttons, rather than stir a hornet's nest :-) There are some car stereo aficionados here that are really into the tech side of things that know how to do it apparently... Search the forum and I'm sure you'll find the details. The local reputable car stereo installers (Car Toys) quoted me almost $600 to install aftermarket on an H2, and stand behind their work. (Normal installs range from free up to around $100)

Fuel pump making noise, definitely jump on that with a genuine GM or AC Delco. Dropping the fuel tank on an H2 isn't bad at all.

Having a Tech 2 is incredibly valuable with these vehicles. Many modules need to be programmed after replacing. Most of the time it's simply inputting your VIN number into it. Such as the switches on the driver's door.... Without programming it, a new one will work out of the box, except it will leave your driver door courtesy light on all the time until it gets programmed. Most dealers will want $180 for that 5-minute job of programming. And that can add up quickly. (Your new fuel pump won't need programming)

Without a Tech 2, using the process of elimination by isolating different circuits/modules is probably your best bet in diagnosing.

 

It uses the map sensor for other things. It’s a good way of measuring engine load. I don’t really understand that though because it could just be calculated off the maf.

 

I know the ECM also utilizes the air temperature as well. Most mass air flow sensors have the sensor for the temperature built in, some systems use an external outsider temperature sensor.

 

dorman sell button replacements kits 76824

 

Just made my day, thank you!

 

Been longer than i thought since I last posted here but between not driving the truck much and some medical issues that are now squared away I finally got a chance to see if I could figure anything out.
just to recap the couple issues i have
keyless unlock doesnt always work, lock works 100% but unlock acts like the system is "asleep" sometimes and after it wakes up it works 100%
air suspension relay clicks like there is a short after turning the truck off and door open when it shouldnt be doing anything but only does it with the door open and it random
fuel pump getting kinda loud
battery holds voltage but seems to have lost capacity and dies quickly
after driving 80 miles perfectly fine, later that day i cranked it and it just felt off even tho it was running smoothly, check engine light came on and it died while sitting at a light, driving it home it was hesitating to accelerate and the tach would drop to 0 if i was going a constant speed, Thru a MAF sensor code but ran fine after sitting for a short while

Got a new battery
checked all the grounds I could find, nothing looked unusual
pulled the BCM, visually looked like new, was hoping just unplugging and plugging back up might make a change, keyless unlock still not always responding
at the SP 205 splice pack, trying to have certain things not plugged in but so far nothing seemed to be an obvious issues, keyless unlock still not always responding
pulled the PCM, all the connections seems good and clean, see below
replaced the fuel pump , no noise and running smoothly

so far still no luck, fuel pump was the first to be replaced followed by the battery, since the battery I have noticed a rough idle and a P0300 multiple misfires(cylinders 7,8) code pop up on my first real drive after it was replaced, cleared it and came it back , also looks like the speedo potentiometer messed up when i pulled the BCM lol

 

amazing how time flies, been there myself, good job on sorting the fuel pump!

Breaking down a list of your outstanding issues:-

1. Air suspension relay clicking with door open
2. Keyless lock system not always working.
3. On old battery MIL light (MAF sensor no code) , hesitant acceleration, tacho readings issue - May be resolved?
4. Speedo potentiometer ?
5. Rough idling, P0300 multiple misfires cyls 7+8

These are likely separate individual issues, although 1 & 2 may be linked, and your comments on SP205 suggests it's not Serial Comms interference/corruption.

1 Air Suspension
"Air suspension relay randomly clicks near the compressor"
Yours should be a single compressor system and I could be wrong about 03's, but the AS relay is normally mounted inside the engine compartment low down on the firewall, fuse box side, so it's not actually close to the AS unit itself. The clicking noises could be coming from the AS solenoid valves operating and not from the AS relay.
There's no direct link between the doors and AS Module, however the BCM does communicate "door status" in theory the suspension will not raise or lower with the doors open. However If there's a problem with a door lock/switch going undetected, then it could happen so this could be a clue. Try and determine if it's all doors or a single door, check also if a "door open" message is being shown when clicking is heard, this may help pinpoint the offending door, the problem may tie-in with comments about the wiring harness.

Does the AS system function normally otherwise?

2 ​​​​​​​Keyless lock system
The key fob radio is located inside the PDM and communicates Lock/Unlock commands back to the BCM. Using a Tech2 to operate the door locks might help determine if its PDM / KeyFob related or something else. For example if it's just the drivers door, the DDM is responsible for:-

• Drivers Door Latch (Door Ajar)
• Drivers Door Lock

DDM's are very prone to water invasion.
Interestingly I have a lazy left rear door lock/unlock which sounds remarkably similar to your problem, could be wiring, lock actuator or even BCM but I've not investigated yet.

3 Battery etc
Regarding the battery, I'm going to put this out there. Over the last 10 years my H2 has had 4 batteries, drain issues and couldn't be left standing for more than a couple of weeks before it needed recharging, eventually I installed a battery isolator switch. I'm pretty good on the technical / theoretical issues but I can't explain why the following fix worked.

My battery has the standard battery side-posts, I wire-brushed them, used no grease etc, but they always looked a dull or "tired" you might say. After being undone and tightened many times the threads eventually wore-out, so for the cost of a few dollars and 5 mins of time, I replaced them - what a game changer, no more battery issues, like a new car !!!
It's as though overtime the battery posts had absorbed contaminants, possibly undergoing some kind of electrolysis until their resistance changed which affected battery charge and discharge. At the moment I'm at a loss to fully explain it, but seriously for the few cents it costs, replace them !!

4 Speedo potentiometer
Not sure about the terminology, do you mean the speedo stepper motor?
If so, it's unlucky to have failed, perhaps when pulling the BCM a bit of movement or mechanical shock took it over the edge, probably would have failed anyway.

5, Rough idling etc
Other contributors have addressed some of the remaining issues, however regarding the radio many of us have successfully fitted aftermarket systems, but I suggest anything connected to the Serial Comms bus needs to come from a reputable manufacturer. I'm unaware of how to map out "stock" or "Nav" radios systems, I'd really like to do that as my Tech2 always complains about the old kit not being present, however think its may be just a security feature baked into GM communications.

 

hey, let me give you more specific information 2003 H2 83K miles

1. Air suspension - works normally , when i replaced the bags after purchasing I pulled the whole unit, cleaned it up and replaced most of the orings. Only issue it has is RANDOMLY when I shut the vehicle off and open any door you can hear sporadic clicking coming from the rear like a relay or solenoid is triggered, and this sporadic clicking is usually started by rocking the truck with a door open like just getting out. close all the door and it will immediately stop. it shouldnt really be doing anything with a door open. if I disconnect the relay under the steering column or disconnect it from the SP205 it doesnt happen but also doesnt work.

2. Keyless UNLOCK - multiple keyfobs same issue. Lock always works 100% of the time Unlock RANDOMLY will sometimes require 20-30 attempts before it works but once it works it works 100% until I have left the truck sit for awhile. I replaced the PDM which the keyfob relearn procedure worked but not exactly like the tutorials I saw online, like it complete the last step but still programed. disconnecting the DDM from the SP205 results in same issue but the driver door doesnt work. its not that a specific door will not unlock, none unlock until the keyless unlock finally just works. the first time it finally catches the driver will unlock followed by the rest of the doors on the next unlock. all of the locks work normally otherwise. I usually keep the interior lights turned off at the light switch but just noticed that they still come on when i unlock the door with the keyfob, shouldnt they never turn on if the switch is off ?

3. replaced the battery since it was a few years old and i think it deep cycled to many times, I normally keep it on a trickle charger but it was dying in only a few days off of it and while I was doing this other troubleshooting I could just see the voltage dropping like a rock after a few minutes even though I had just completely charged it the previous night.

4. IC speedo, yea the stepper motor, I forgot the term and yea thats just bad luck pulling it out, ive replaced one before on a 05 Suburban and actually still have a spare, just complaining more than anything lol

5. Rough Idle - from what I understand this shouldnt really be BCM related or issue 1 & 2 but I noticed it after replacing the battery. Its pretty consistently giving me a P0300 multiple misfire code now, its like something needs to be relearned, I just swapped 5 & 7 plugs wires and coil and didnt seem to show a difference but does feel like its idling better, I also disconnected the battery while I was doing this then let it idle for about 10 min. About to go drive it and see if it went away.

I think the most annoying thing is that Im not sure if any of this has anything to do with when it about left me stranded when it tossed the MAF code. The only other codes I got around that time were i think P03?? for a misfire but I dont remember exactly what it was

 

try tightening the intake and throttle body bolts. maybe they are loose. also check the intake clamp. it tends to fold over when putting it back onto the throttle body and lets air past the MAF sensor. also if you have a long screwdriver or a mechanic stethoscope listen to the tap of the injectors especially the misfire ones. if they are quieter then the rest try tapping on them to free them they might be sticking. add a good injector cleaner to your fuel if thats the case. with that low miles they might be varnished. hopefully its not rodent damage from sitting.

 

1 AS

• The clicking sounds are probably the airbag solenoids operating as if the AS is trying to level the ride height - presumably the compressor isn't running?
• Disconnecting from SP205 will cut Serial Comms to the AS Unit, it will not function without comms.
• You are correct, the AS should not operate with a door open (except the tire inflator) the questions are why and how? It also shouldn't operate with the engine idle.

• Check the earth terminal on the AS Unit.
• Have you had any issues with the front wipers? - a faulty wiper motor can produce back-feed voltages which can cause the interior lights and radio to remain on, it might be related.

2 Locks

• if you sit inside the vehicle and operate the DDM door lock manually, do all the doors lock and unlock correctly?
• As for the AS unit, disconnecting the DDM via SP205 will disable it - of course as there's no comms
• Not sure about the interior lights/Keyfob issue, might be related to vehicle settings
• Driver door unlock, then remaining doors on next unlock may be related to vehicle settings
• Do you have an aftermarket alarm system or remoted start fitted?

3 Battery
Batteries have two essential but differing characteristics:-

• SOH (State Of Health) a measure of it's capacity, this is can only really be determined using a smart battery tester, effectively it's a measure of a battery's internal resistance.
• SOC (State Of Charge) is effectively the voltage across it plates and can be read directly with a voltmeter.

A battery's capacity can reduce with age, it's terminal voltage (SOC) may read GOOD but it's ability to crank an engine may be BAD (SOH) As mentioned the battery terminal screws play a much more important role than generally perceived as these screws are become "resistors" in series with the battery and can increase it's effective internal resistance and lowering its capacity.

The H2 needs a good stable 12V supply to run it's various control modules

5 Rough Idling
bronxteck is offering sound advice on this, I'd be tempted to follow his lead.


Finally, the strange activity of the AS Unit is perplexing, provided (as mentioned) it has a good ground connection it relies on 3 main things:-

1. Serial communications with the BCM to provide various control data such as door/open closed status, vehicle speed etc
2. BATT+ voltage supply, this is always HOT and comes via HVAC ECAS 10A Fuse (under the hood) and required by all the AS solenoids including the compressor AS relay drive.
3. IGN 3 voltage which is only HOT when running and comes via the 4WD 15A Fuse (left of dash) circuitry inside the AS module uses this to determine if the engine is running.

The airbag inlet and exhaust solenoids (3off) are driven via the microprocessor inside the AS ECU, this has to be done deliberately which means the ECU has determined the engine is running and levelling is required, the compressor should also be running but it isn't, hence its perplexing.

Does rocking the vehicle with the tailgate open cause clicking sounds?
What happens when the tire inflator switch is activated with the engine off.