Originally Posted by knewblewkorvette

Originally Posted by JR-01

Is there any mods to the car? Aftermarket accessories?

Originally Posted by 8VETTE7

Clunk under the passenger head light when you connect the battery is normal. It is the head light control module (HCM) powering up. However they are known to go bad and since they are always powered could be the source of a significant electrical draw. You can eliminate it from the equation by disconnecting the two electrical connectors to the module. Do this with the battery disconnected. You can also just remove fuses 3 and 4 in the under hood fuse box.

Once you have disconnected power to the HCM try reconnecting the battery. There will be some small spark that occurs when you reconnect the battery as there are many electrical circuits that are powered up when the battery is connected. I suggest that you remove the HCM and carefully examine the outer case for cracks in the plastic. These are not uncommon and can allow moisture and dirt into the electronics of the HCM. If you find cracks in the plastic you are going to need to replace the HCM. A new one is hugely expensive. Look for a good used one from Ebay or Marc at Vettenuts.

http://www.vettenuts.net/index.php?l...w&p=contact_us



The other symptoms are best diagnosed by pulling and posting the codes. If you have never pulled codes on your C5 here is how:

https://youtu.be/SviRjIsy9G4


Post ALL your codes including the H or C or HC that follow each 5 character code. List the codes under the sensor that they show with. ie 10 - PCM or 28 - TCS or 40 - BCM ..... etc .....

If any sensor shows NO COMM next to it post that info also.

Originally Posted by knewblewkorvette

Originally Posted by 8VETTE7

Unless you meant that the final current draw was 0.021Amps you have a parasitic current draw and that is the reason for the battery doing dead in a few days.

Here is a cut and paste from a Bill Curlee thread on C5 current draw:

The correct BCM current draw should be 30 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.

Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendancy stay on
and cause this issue.

Also pull the fuses for the Bose system amp.

Examine the car in the dark for lights staying ON.

Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.

Look at my electrical stickey. I think I cover this in detail in that post.

There are several COMMON things that cause excessive current draw

-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off


If the tips at the end of the above clip do not narrow down the cause of the current draw then you will need to go through a process of removing fuses one at a time until you find the cause. Here is a link to a thread about that process, also from Bill Curlee:



http://forums.corvetteforum.com/1567522286-post590.html


To avoid confusion I will address the codes in a separate post below.

Originally Posted by 8VETTE7

The two TCS codes have to do with brake fluid pressure issues. I would check the wiring and connector at the brake cylinder for damage and to make certain the connector is making good electrical contact to the pressure switch. If the electrical connector and wiring is good the there are two possibilities. One is that the pressure switch is bad. The other is that The EBCM is a problem or the wiring from the brake pressure switch to the EBCM is bad somewhere along the path.

I can post the wiring diagram and the diagnostic tree for these codes from the shop manual if you need it. Let me know


For the codes for the left and right door control modules (LDCM and RDCM) I would get the battery drain issue cleared up first and then once the battery is functioning correctly (not being drained) I would clear all your codes then take the car for a nice ride and then BEFORE you shut off the engine, pull the codes. To pull codes with the engine running you must use the RESET button to clear any messages displayed in the DIC and then pull codes as normal. Any codes that have returned are in need of attention. Post those back here. Many of the LDCM and RDCM codes that you have (or possibly even all of them) are due to the battery being low.

Originally Posted by 8VETTE7

The two TCS codes have to do with brake fluid pressure issues. I would check the wiring and connector at the brake cylinder for damage and to make certain the connector is making good electrical contact to the pressure switch. If the electrical connector and wiring is good the there are two possibilities. One is that the pressure switch is bad. The other is that The EBCM is a problem or the wiring from the brake pressure switch to the EBCM is bad somewhere along the path.

I can post the wiring diagram and the diagnostic tree for these codes from the shop manual if you need it. Let me know


For the codes for the left and right door control modules (LDCM and RDCM) I would get the battery drain issue cleared up first and then once the battery is functioning correctly (not being drained) I would clear all your codes then take the car for a nice ride and then BEFORE you shut off the engine, pull the codes. To pull codes with the engine running you must use the RESET button to clear any messages displayed in the DIC and then pull codes as normal. Any codes that have returned are in need of attention. Post those back here. Many of the LDCM and RDCM codes that you have (or possibly even all of them) are due to the battery being low.