lilsage15 Posted December 15, 2011 Report Share Posted December 15, 2011 So I started up my SS yesterday and noticed that something was up. The engine seemed off and the electronics weren't all working that great. Then the message came up in my message panel saying that my engine was running at half power... So I shut it off real quick and went to see if it was in the book. It said that something was messed up in the coolant surge tank. I then went and poped the hood and there wasn't any steam or stuff that's unusual so I went and tightened the coolant surge tank pressure cap and it was loose but not a whole lot. I went and checked to see if there was any coolant in the actual tank and there was and it was over the line. I ended up just checking everything and couldn't see anything wrong so i went and turned the key and the check engine light went off and everything is fine now but does anyone think I should take it over to my mechanic so he can check just to make sure nothing bad happened? Quote Link to comment Share on other sites More sharing options...
MARTYW Posted December 15, 2011 Report Share Posted December 15, 2011 I read on here that there is a safety mechanism programmed in these trucks that will limit the power of the trucks when that are certain things going wrong. Try a search. I know it is on here somewhere. Good luck! Quote Link to comment Share on other sites More sharing options...
lilsage15 Posted December 15, 2011 Author Report Share Posted December 15, 2011 I read on here that there is a safety mechanism programmed in these trucks that will limit the power of the trucks when that are certain things going wrong. Try a search. I know it is on here somewhere. Good luck! Yeah I read it in the book, it only lets the engine shoot a couple pistons and limits the electrical to keep the temp down. Plus it wont go over 25 mph Quote Link to comment Share on other sites More sharing options...
diggerdan11 Posted December 15, 2011 Report Share Posted December 15, 2011 My wife has the same thing happen in her tahoe a about a week ago. She started it drove a block, stoped and when she started the tahoe again it said reduced power. She drove home, and I started the car, the check engine light was on but it did not say reduced power. I drove it around the block a couple times and no problem. I decided to mess with it the next day. I started her up and the light was off and no problem. The tahoe is leaking coolant but we are having trouble finding exactly where from, so we have just been filling it up. When she came home with that issue the coolant was a little low but not that low. Quote Link to comment Share on other sites More sharing options...
T-Bag Posted December 15, 2011 Report Share Posted December 15, 2011 (edited) Limp mode is caused by the PCM throwing a code. Particular codes trigger limp mode in order to protect the motor/trans from damage. Pull the code and go from there. Edited December 15, 2011 by Bad Ass Silvy (see edit history) Quote Link to comment Share on other sites More sharing options...
lilsage15 Posted December 15, 2011 Author Report Share Posted December 15, 2011 My wife has the same thing happen in her tahoe a about a week ago. She started it drove a block, stoped and when she started the tahoe again it said reduced power. She drove home, and I started the car, the check engine light was on but it did not say reduced power. I drove it around the block a couple times and no problem. I decided to mess with it the next day. I started her up and the light was off and no problem. The tahoe is leaking coolant but we are having trouble finding exactly where from, so we have just been filling it up. When she came home with that issue the coolant was a little low but not that low. Hmm well I don't believe mine is leaking at all but Ill keep a look out for it. Quote Link to comment Share on other sites More sharing options...
canadianVRss Posted December 20, 2011 Report Share Posted December 20, 2011 (edited) Our coolant systems are touchy. I took my intake off awhile back to get at my oil pressure sensor and I had to undo the little coolent line attached to the throttle body. When I was putting everything back together I figured I'd better run her with the coolent resivour cap off to help any bubbles escape back to the resivour and avoid any hot spots. It warmed up and I put the cap back on silly move, because now the pressure in the system is at atmospheric when HOT. So when the system was cold it was under vacuum. The truck DID NOT like it at all. The choke was always on and it would never drop below 1000 rpm idle for some reason. I had to wait until the truck was cool and then crack the resivour to get it back to atmospheric when cold. The resivour took a massive gulp of air, then all the problems went away. I think the little coolent line going to the throttle body must some how affect the choke with coolent pressure. But I always thought choke was controlled by the PCM. Edit - not exactly sure what im getting at with this post. i think because your resivour cap was loose your coolent system pressure was at atmospheric and wasnt able to pressure up. its not a far stretch to think it would throw a code, the way my truck was acting im suprised it didn't. my truck would do 20km at idle and when i would brake it would still try to go for a few seconds. this has me covinced that you need coolent pressure to kill the choke and make it run nomally once warmed up. that coolent line to the throttle body must do this. which makes me wonder about the guys who have done the TB bypass mod. but like i said, i thought the choke was controlled by the pcm. hopefully someone will know and post........ steve??? i know you said the code went away but just to be safe crack the resivour cap when its cold to make sure you dont have any vacuum pressure in the system. Edited December 20, 2011 by canadianVRss (see edit history) Quote Link to comment Share on other sites More sharing options...
LSR Mike Posted December 22, 2011 Report Share Posted December 22, 2011 I had the reduced power mode come on with a CEL, punched the Onstar button, bad output from TPS#2 diagnosed. shut it off for 30 seconds, Restarted, ok for Now. going in the shop after Christmas. Quote Link to comment Share on other sites More sharing options...
Sik-rod-yo Posted December 22, 2011 Report Share Posted December 22, 2011 (edited) If its reduce engine mode it's one of two things eather your throttle body taking a shit or ur tac module but first make sure tb conector is plugged in right then go from there Edited December 22, 2011 by jgpclone (see edit history) Quote Link to comment Share on other sites More sharing options...
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