Hi guys, its been a long while since I have posted. Went bmw, came back to trusted and beloved Acura. Its's an 05 RL, and its been in my family since 2008 and now its mine <3.

To skip small talk, I have an annoying issue with the car. The sh-awd light comes on randomly.. generally after I drive the car for about 15 minutes. After it turns on,and im in fwd only. It's winter, i live in Toronto, Canada, lol and i really need awd. My check engine light is also on, the code is for a faulty or most likely clogged EGR valve. I might have dreamt it, so please correct me if im wrong, but i remember reading somewhere that the two issues my car is having might be interrelated......or rather the faulty egr valve is somehow causing the sh-awd to turn off.

Please chime in with any feedback. I really want to get this fixed, i just want to be more informed on what's going on.

Thanks in advance!

 

What's the code? Also, have your battery tested to see if that may be a suspect..


Aside from checking the battery, unbolt the EGR and clean the shit out of it..

 

I don't think CEL which indicates an emission issue will disable SH-AWD. Typically only drivetrain errors cause that.

How old is the battery? A weak battery, even one that passes an Autozone test, will cause all sorts of errors even including SH-AWD. The cold weather makes the battery less conductive, so that could be your issue.

 

I just replaced an o2 sensor & every time the CEL came on it would disable SH-AWD..

 

^^his shawd light is coming on.

My vote doesn't count im an amateur, but I'll call battery as well. I got one 3 months ago with considerably higher capacities than the oem one, made for hard cold weather, and even when temperatures were not so cold and i honked for 2-3 seconds at a very smart driver, cmbs light came one for a few seconds then left. I'm guessing it means the current to that sensor reduced, then came back.

I'm wondering if the central computer isn't causing less current distribution unnecessarily.

 

^The SH-AWD light comes on when the rear diff disables. That's how you know. This is why having the car helps. Been almost 4 years since I drove mine.

 

The best way is to pull the codes, if any, from the SH-awd system to know for certain. Until then it is just a guessing game.

Many inputs and outputs (sensors, actuators, etc) for the PCM are also just as critical for SH-awd control unit in order to function properly. One fault may or may not trigger multiple warning lights to illuminate on your cluster/mid/navi display. It is dependent on design/programming and varies from model to model. I have experienced an egr malfunction cause a awd failure.

Another example would be a faulty vehicle speed sensor which is monitored by the PCM, is also critical for the following- VSA/ABS, SH-awd, navi system operation. In this case one sensor can cause a powertrain, drivetrain and navi/location issue. Good luck.