My keyless features stopped working right around the time the sunroof drains on my 06 G35X decided to dump gallons of water into the car, wetting areas under the glove box, and I'm assuming the keyless module as well. Dried the car out. Tried new batteries in the FOBs. Tried the FOB programming steps. Nothing, keys aren't seen at all.

So, the question is; will replacing the keyless module solve this issue without fuss, or would I need to take the car to the dealer for reprogramming after replacing the module?

I appreciate any insight.

 

There is no separate key module, it's all handled through the BCM in the driver footwell.

 

I have a keyless module under my glove box (28595-AC300). That is what I am referring to, and that is what I believe had water leak onto it / possibly shorted. I assumed it has a role in the keyless functionality chain of command, but I will defer to your expertise on the matter.

 

Ohh my bad, I read all that stuff wrong and assumed it was a non-functional key start system. The engine starts and runs fine though yeah? Just the KEYLESS ENTRY system that isn't working?

 

Also, do the power door lock buttons work inside the vehicle? Does the horn work? If so then I would disconnect the battery, unplug the keyless entry module, put the battery back on and turn the ignition to ACC then test the YELLOW WIRE for voltage, I think it's 5v but it might be 12v, most of the power coming out of the BCM to various things like that operate on the 5v system.

As for that receiver module, yes it's plug and play and doesn't require any sort of programming.

 

Ah. Yep, car starts and runs fine if I manually use the key in the ignition. It's the keyless features that were behaving intermittently one day, then stopped working completely that same day. It was shortly after that I discovered the soaking wet passenger floorboard, so I just put two and two together.

And, while I have your ear, any advice as to how to clean out the sunroof drainage hoses? Mine run down to the kickpanel, behind the metal of the car, with no seemingly possible / sensible way to access. Sure, I can clear any obstruction up at the headliner, but if the obstruction is down at the outlet, forget about it.

 

Yep. Horn, power locks, and everything else functions as normal, which is why I was zeroing in on the module itself.

I had planned to do exactly that this weekend (unplug and test power, but the weather isn't cooperating) before officially going the eBay route. Just wanted to make sure that, if I do go the eBay route, I'm not in for more headache than I realize. Glad to know it's plug and play.

 

Ok so the EASIER way is to get a compressor air spray nozzle and put a bit of flexible hose on it so you can spray it directly into the sunroof drain from the top AT THE SUNROOF, this way you don't have to disassemble anything. Spray some brake cleaner/degreaser into the tube first then shoot it through the system with the air nozzle. There are 4 sunroof drains, one at each corner so make sure to do them all.

If it's plugged up badly and you can't get the flex hose on your nozzle to mate up tight into that hole then you can do like I did and cut the sunroof drain hose in the middle where it's accessible near the a-pillar and used a combination of brake cleaner and compressed air to de-crud and blow it out. Then just put a brass barbed coupler and a couple hose clamps on it to patch the hose back together. Use some gorilla duct tape to tape it tight up to chassis metal so those clamps don't rattle in the future.

When you're done take a cup of water and pour directly into the drain to verify it's working, the fronts drain out pretty much right near the wiper arm in the cowl, rears I have no idea it drips under the car.

Depending on which chassis you have depends on how easy it is to access those drain hoses, the 2003-2004 coupe, 2005-2007 coupe, and 2003+ sedan are ALL different from one another. Strongly recommend trying to blow it out from the top at the sunroof because that's the most accessible.

 

That was going to be my first attempt to solve it; slap some cleaner in the line and try to blow it out. From there, it's basically... pull down the headliner and make new drainage hose runs. My hoses are completely behind the metal of the car, even in the a-pillars. The only part of the hose that's visible is up at the headliner. Mine don't drain out behind the dash / near the wiper. They run all the way down behind the bolted on metal of where the kickpanel piece goes. As far as I'm concerned, it was not designed to ever be accessed.

So it's either option 1 or 2 for me.

I appreciate the insight.

 

The hose itself probably isn't the problem, it's almost ALWAYS right where it goes through the grommet outside the vehicle.

 

Going to have to check behind the tire well / fender to see if that's where it drains out.

That aside, I've had no luck addressing the keyless functionality. Checked for power in the wire to the module. Power is good. Disconnected the battery and checked fuses. Fuses are good. Disconnected the module, looked for corrosion on the pins. Nope, all looks good. Plugged the module back in, reconnected the battery... boom, everything worked.... for 5 minutes. For 5 minutes ALL the keyless features (doors, keyless start, etc) worked normally. Walked 20 feet away from the car, doors locked and unlocked with ease. 5 minutes later, back to nothing.

Okay, so maybe the module is bad and it just had one last hurrah. Bought a new module. Nope, still nothing.

So now I don't know where to go from here. Bad keyless entry relay fuse box module?

 

That's weird, my gut feeling is a failing capacitor on the BCM but I would try doing things like.

-Disconnect/reconnect battery leaving everything else plugged in, does it work for 5min then stop working?

-Plug in an OBD2 scanner, see if it too stops connecting after 5min too.

-Disconnect battery and unplug/inspect the BCM harness, particularly pins 18, 19, 20. If they all look good try splicing pin 18 (black wire) and grounding it out to another point on the chassis just as a supplementary ground

 

I cannot repeat the result. It worked for 5 minutes that one time and now never again.

I have attempted numerous times to disconnect / reconnect battery / keyless module to no avail.
OBD2 scanner stays connected just fine.

I figured the next stop is something going on with the BCM, which is an area I wanted to avoid. I guess I'll give it one last effort before accepting that... it's just an old car.

 

Ok time to dig into the wiring, firstly, disconnect the battery, then the keyless module, plug the battery back in, key ON and test for voltage at the keyless module harness M78.

Yellow wire on pin 4 should have 5v to ground (chassis ground on the car somewhere) I think, most BCM components operate at 5v, might be 12v though, hard to say.
Black wire on pin 1 should have continuity to ground.

Measuring voltage across pin 1 and 4 should also produce the same voltage signal you read earlier when going pin 4 to ground.



If you DON'T have ground then the next step is to measure those same wires by backprobing the BCM harness, if you don't have actual backprobe leads then just use a paperclip to backprobe and hold your meter lead up tight to the backprobe (ideally with aligator clips if you have them) but be careful not to ground out the voltage pin. Here is the BCM harness, colors are the same but it will be pins 18 and 19 as shown in the previous diagram.



Next is to check continuity of the circuit. Disconnect the battery again, disconnect the BCM harness. Measure resistance from:

BCM pin 19 to Keyless module pin 4, yellow wire
BCM pin 20 to Keyless module pin 2, blue wire
BCM pin 18 to Keyless module pin 1, black wire

If you don't have continuity on one wire then just cut it at the BCM and keyless module and fish a new wire up through the dash somehow, solder/splice both ends. Use soldershrink splices if you don't feel comfortable using an actual soldering iron, all those ones need is a heat gun (or a lighter but don't turn the insulation to smoke).

If you DO have continuity on all three wires, or if you don't have voltage/ground at the BCM then the problem is likely a failed BCM but there's some other trickery you can try by pulling power or ground from another BCM output. As long as the SIGNAL pin is still working then you can make it work even if the power or ground signal aren't working.