I have a 2009 H3 Championship (Alpha/Offroad) with 127k miles. Crappy azzed OEM battery terminals have been replaced with quality aftermarket terminal connectors.

This month the remote keyless entry (RKE) sensitivity took a nose dive. A month ago it was working fine from 30-40 ft away and now you have to be standing right beside the truck for it to work. Last week I got the related SERV TPM message. Scanner shows that the BCM has lost signal from all the wheel speed sensor (C0750, C0755, C0760, C0765) pointing to the antenna/BCM described on the forums here.

I have no other BCM issues. I did have a clogged sunroof drain on that side this past summer (now fixed) but perhaps the damage is done? My first troubleshooting step was to access the BCM and unplug, inspect and reconnect the antenna connector. No visible sign of corrosion in the connector, but no change in performance afterwards either.

Next planned step is to remove the BCM entirely and clean both the harness-side and the BCM side connections using CRC electronics cleaner. This should help if the BCM is not getting good power/ground through those connectors. Of course, I'll disconnect the battery before I do this since BCM has always-on power inputs. I'll inspect the battery terminals and put the battery on charge while I'm doing this (Optima Redtop is 3.5 yrs old).

Anyone have other suggestions for other things to try? Can the antenna itself go bad? Could this be cold weather related? I've seen some reports of spraying the BCM circuit board with the CRC cleaner - anyone have experience with that? Other suggestions for things to try before going the BCM route?

Looks like both the antenna (24300221) and BCM (20987862) are discontinued - anyone have a NOS source for them?

TIA
NMH3

 

 

When you scanned it, was the truck moving or immediately after you stopped moving? TPMS do not transmit when stationary for so many minutes unless detecting a PSI change (letting out/adding in air).

No mention of a fresh key fob battery change? Do we assume the fob(s) are functioning?

Try CRC before removing the BCM to all the connections. The antenna itself is an unlikely problem. If the BCM got wet in your dry climate, it just took a while to corrode connectivity.

 

Thanks Doc.

Scanned immediately after moving. Cleared the codes, but they all returned after about 20 minutes more driving.

Didn’t try a new remote battery, but will do that to be sure. I’ve ***-u-me’d the issues are related, but get your point. Simple things first.

What do you mean by trying CRC before removing the BCM to all the connections? Do you mean before opening up the BCM and using CRC on the board, or something different? I have to disconnect the connectors before spraying them, so not following your suggestion here.

Haven’t pulled it into the garage yet to give stuff a try. Appreciate your guys ideas and input.

NMH3

 

Try deoxit instead. Open BCM and clean the board with it. Clean all the associated ground points and the connectors. Id also DVM the C105 & C106 under the hood (located at brake abs area and behind air box). Make sure to remove the multi harness ground and give each a gentle tug test... lol don't jimmy jam em so hard you rip the wire just a gentle tug. Clean the area and the multi ground connector. Then reinstall. Clean the BCM really good and its connectors. Try again. Good Luck.
And as always lol check key fob battery 1st.

 

Disconnect and spray connections and antenna (no removal) then after dry, see what you have. Well, I guess if you disconnect the antenna that itself may be "removed". If the spry and reconnect makes any difference, you still should consider doing the removal and BCM board. Clean up the grounds as well. As old as these trucks are getting, they need attention.

 

I am having the exact same issue with my 08 Alpha, tried all the cleaning the antenna connections on the BCM and dielectric grease with no success. I found a substitute antenna and ordered from GM. Hasn't come in yet, as soon as it does, I'll let you know, and give you the part number.

 

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Ok....received the new BCM antenna from GM. Part number is 22936091, just to find out the plug is slightly different, I had to file off the 2 little proud spots on the BCM plug to get it to plug in. Once plugged in, I could get the Key Fob to program and work,, I would consider the range to be kind of weak compared to the newer fobs of today {works all the way around the truck, but not from more then a car length away}. Plugged the old antenna back in {which had not worked at all} it now works with REALLY limited range {pretty much just in the truck} ..........So with the new antenna it works better then the original, although I'd still say limited to a car length away. I really don't know how well these things worked when new, the BCM probably has lost a few steps over the years as well I'm guessing

 

My FOBs regularly work from at least 30-40 feet away even from inside my house (albeit with the truck visible through my window). Intermittently, however, it will be a b***h and not work at all, even standing right next to the truck. Of course, 30 seconds later, it works great. PITA.