Clicking near rear end....

Often times when we shut our 2003 H2 off and get out, we will hear a clicking sounds ( 5 - 7 times). I listened underneath when it was happening, and it appears it is coming from the "computer" components located underneath / behind the rear bumper.

Does anyone know what these computer components control , or what the sound may be ?

Thanks in advance

I would think any clicking sound could be the exhaust cooling. Other than that, something for the EVAP system maybe?

Thanks !

We do have a Magnaflow on it, but it is clearly coming from that "computer" box that is covered up under there :):)

The dealer stated they could not duplicate the problem :) Of course, when we picked it up, drove it home, it did it :):)

Mike

I have the same exhaust on mine and no problem. I dont know if the purge valve is located there or not. Normaly that would tag the check engine light. This is just a guess, but maybe the gas cap is not venting right and too much pressure is building up causing the valve to work overtime.

We have a few on this site with some good tech info. Maybe they will chime in.

Cool !!!

Thanks for the ideas !!!

Mike

I suspect it to be normal..Probably the emissions evaporative controls either; 1. pressurizing the system looking for any leaks, or 2. it's the fuel pump shutting down..Course I have an H3 and don't have a clue what it could be....But my Land Rover I had, would do that for about 30 secounds to check the fuel system for integrity.

I was going to respond in a funny way to Dennis, but I'm kinda brain dead this morning.

do you have an air bag suspension or springs? i don't know what computer stuff in the rear you're talking about, but would guess it has something to do with the compressor, assuming you have one.

Hi. found this site by searching for clicking noise.
I too have this noise on my 04/H2. It just started. It only happens after it has been driven abd only lasts for seconds after you park.
sounds like a solinoid clicking. Took it to the dealership "didnt make noise" service guy said it could be the air ride pump? but wasnt sure.
My noise has stopped in the last few days as I have the back loaded with some parts. I wounder if this added weight has anything to do with the noise stopping?
Would appriciate any more opinions

Thanks
Mark

My Avalanche did this, My SRT-10 did this, my H2 does it ... Either I've had 3 trucks with the same problem or this is normal. I've never reflected on it much ..

Could be the Heat Shield. There is a TSB for this:

Subject: Popping/Snapping Noise When Vehicle is Hot, at Idle, or Immediately After Vehicle is Shut Off (Replace Muffler Heat Shield) #03-06-05-008C - (10/28/2005)


Models: 2002-2005 Cadillac Escalade, Escalade EXT

2003-2005 Cadillac Escalade ESV

2002-2005 Chevrolet Avalanche, Suburban, Tahoe, Silverado, Silverado HD

2002-2005 GMC Yukon, Yukon Denali, Yukon Denali XL, Sierra, Sierra HD

2003-2005 HUMMER H2

with 4.8L, 5.3L, 6.0L , 8.1L Gasoline Engine (VINs N, U, T, V, Z, G -- RPOs LQ9, LQ4, LM7, LR4, L59, L18 )

OOPS, Here id the rest of the TSB:

Condition
Some customers may comment on a popping/snapping noise from underneath the vehicle at idle or immediately after the vehicle is shut off. Some popping/snapping noise from the exhaust system during cool down is a normal condition.

The noise may be intermittent depending on the outside temperature and or temperature of the exhaust system at the time of testing.

Cause
As the exhaust system warms and cools, the muffler and the muffler heat shield expand and contract at different rates and may cause a popping and/or snapping noise.

Some popping/snapping noise from the exhaust system during cool down is a normal condition. The customer should be made aware that this service procedure is designed to reduce but not eliminate all exhaust system popping and snapping during cool down.

Correction
DO THIS
DON'T DO THIS

Install a new heat shield and straps on the existing muffler.
DO NOT replace exhaust system components other than the muffler heat shield.


Follow the service procedure below to correct this condition.

Important: Some popping/snapping noise from the exhaust system during cool down is a normal condition. The customer should be made aware that this service procedure is designed to reduce but not eliminate all exhaust system popping and snapping during cool down.

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information (SI Document ID #737171).
Caution:

• In order to avoid being burned, do not service the exhaust system while it is still hot. Service the system when it is cool.

• Always wear protective goggles and gloves when removing exhaust parts as falling rust and sharp edges could result in serious personal injury.


Remove the nuts securing the muffler to the catalytic converter.
On 6.0L and 8.1L equipped vehicles only, loosen the exhaust pipe clamp.
Important: Do not use oil base lubricants on the rubber exhaust hangers.

Apply a soapy solution to the exhaust pipe hanger rods in order to ease the removal of the exhaust hangers.
Pry the exhaust hangers free from the exhaust pipe hanger rods.
Important: It is not necessary to remove the muffler from the vehicle to replace the muffler heat shield.

Reposition the muffler to gain access to the muffler heat shield.



Notice: Use extreme caution not to damage the muffler when removing the heat shield from the muffler.

Using an air-powered hack saw blade, or equivalent, cut off the existing muffler heat shield just as the heat shield rises off of the muffler. See the illustration above.
Remove the heat shield from the muffler.
Hammer flush the remaining heat shield to the muffler.



Important:

• The new heat shield should not come in contact with the remaining muffler heat shield.

• The new heat shield should not come in contact with the horizontal lock seam on the muffler.


Install the new heat shield (see parts list below) onto the muffler as shown above.



Install three straps, P/N 10391259, so that the strap screw head will be located on top of the muffler.
Tighten

Tighten the strap screw to 4 N·m (35 lb in).





Cut off the excess strap material and bend the strap over the strap screw head as indicated above.
Remove the exhaust pipe clamp.
Important: ONLY 6.0L and 8.1L equipped vehicles require a new exhaust pipe clamp, P/N 15103174.

On 6.0L and 8.1L equipped vehicles only, install a new exhaust pipe clamp, P/N 15103174, on the exhaust pipe.
Reposition the muffler in the correct position.
Slide the muffler forward into position, aligning the studs with the rear of the catalytic converter.
Install the nuts securing the muffler to the catalytic converter, but DO NOT tighten at this time.
Apply a soapy solution to the following areas in order to ease the in