Driving in the hwy, doing about 60. All of a sudden, engine would not rev and "reduced engine power" flashed on the screen. it would not go over 20 mph. I pulled over, shut it off, restarted it, and it was fine for another 10 min when it did this all over again. I just unhooked the battery for 10 min, but after about 15 min of driving it continues to do this! Any ideas? There are many threads about this issue on cadillac forums, but no one has posted how they have actually fixed it! It seems like the car is trying to limit its self because it thinks something is wrong. common problem, but how is it fixed?
I have seen that on my 2004 Tahoe twice, both times when towing. On the Tahoe it is a problem with the drive by wire servo at the throttle body. Some of them have screwed up wiring that needs to be fixed or replaced (I think in our case the harness was installed too tight and would get pulled when the engine moved). I ignored it and it hasn't happened again. It's been 4 years now...
Many many issues will cause this code. You will need to scan the modules and see what codes are active or stored. I suspect it could be a torque converter or transmission issue. Seem to remember I have replaced quite a few of them. Also could be an accelerator pedal, or throttle body, cam or crank sensors, ignition coils, timing issue, ecm problem. Heck, the car could even be running over temperature, not enough to overheat, but enough to throw it in limp mode. Put a scan tool on it and see what it has. And a proper one, not one of these cheap code readers, they can cause more problems, I loathe them in the Mercedes-Sprinter industry.
My 04' Silverado 5.3L has done this to me since I bought it, however it ONLY does it when we are below 20 degrees outside and I haven't let it warm up before taking off. I have yet to figure out why it does it, but I keep my snap on scanner in my truck and as long as I keep the "manufacturer specific" code cleared out then it won't do it. So frustrating....
Go to the Cadillac forum, the 3.6 has had issues with the cam chains (it seems that there was a bad batch, heat treating issues) that will put them into reduced power mode.
Is your car out of warranty? We had a Pontiac G6 with the same engine and this was a recurring problem. It was an error with the throttle position sensor IIRC. It happened several times and we actually eventually got a payout from GM. If it is that problem, which is common, There is a tech bulletin regarding the parts.
