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Ok....so heres the deal

 

 

 

Hopped in my 2004 Silverado tonight and went down the highway, probably 10 miles or so doing around 70-75ish. Went to get off the highway and the DIC says "Reduced Engine Power", the check engine light comes on and stays on, and my truck basically tells me I am going to go 15 MPH and I am going to like it. I couldn't go any faster. Almost got rear-ended trying to get into a parking lot. I got to the lot and shut off the truck. Got out and checked for leaking fluids. Checked the oil, it was fine. No leaks. The coolant tank was pretty full...the usual level. Everything appeared to be fine. I restarted the truck several times and couldn't get anything to change. I Checked the coolant reservoir and unscrewed the top and relieved the pressure. I tried to start the truck again, the check engine light went off and the message went away. I nursed it back home. Once I got home, I checked agian. No leaks. But the hoses are scalding hot. I realize they will be pretty hot from driving, but this seemed hotter than normal. Any ideas what the problem is? Could the Dex Cool anti-freeze be gelling up? (I thought I heard some people having a problem with the pinkish/red stuff). Any ideas would greatly be appreciated. Have an appointment with the dealer tomorrow. Would just like to go in prepared...somewhat. Thanks.

 

-Brian

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I thought the reason GM created this mode is to allow limp-home of a vehicle which lost its coolant.

 

Did you see anything unusual on the coolant temp gage?

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I thought the reason GM created this mode is to allow limp-home of a vehicle which lost its coolant.

 

Did you see anything unusual on the coolant temp gage?

 

<{POST_SNAPBACK}>

 

 

 

 

Yea I looked in the manual while I sat there being really PO'ed, finally found the right section in the manual. It said it was related to a coolant problem. Some kind or protection for the V8 engines that shuts half the cylinders down to prevent damage or something. My temp guage was the normal 190. Thats what didnt make sense to me. If it was overheating, why did the guage show normal. I guess the guage could be bad. But after I de-pressurized the coolant tank (either that or the sitting there for 10 minutes), the engine light went out, and the message went away and I was able to drive it home. But like I said, the hoses seemed hotter than normal. Maybe its just me, I dont make it a habit of feeling my hoses after I drive the truck. Just seemed like the whole engine compartment was hotter than normal when I opened the hood.

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Well the fact that you were able to depressurize the system says it wasn't above 220 or 230. I think you'd have to get it pretty hot to make it think it lost its coolant.

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:driving:

Well the fact that you were able to depressurize the system says it wasn't above 220 or 230.  I think you'd have to get it pretty hot to make it think it lost its coolant.

 

 

 

 

 

Thats kinda what I was thinking, but Im no mechanic so I figured I'd limp it home and ask you fine folks who have a clue what you might think it is cuz I'm stumped. :sigh:

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I wonder if maybe your thermostat had stuck shut. Was this drive where this happened starting from a cold engine?

 

Hopefully there'll be a code in the computer that will explain what happened.

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I wonder if maybe your thermostat had stuck shut.  Was this drive where this happened starting from a cold engine?

 

Hopefully there'll be a code in the computer that will explain what happened.

 

<{POST_SNAPBACK}>

 

 

Yea, engine was cold...hopped in the highway...probly a good 10 miles or so, went to get off the highway and thats when it happened. Dumb question here....but if the thermostat stuck shut, wouldnt the temp guage read higher than normal? Even if only for a few minutes? I drive an international flatbed for work, so I am always watching my guages...I didnt notice any higher than normal readings on the guage.

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When (if) it gets above 260 you get a message like "engine hot" in the DIC. Then I think at about 265 you get "engine overheated". But even then it doesn't go to "Reduced power mode". I don't know how hot it has to be to do that. Above 270.

Edited by mmmikkke
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Ok, so first off...after dropping off my truck...the dealer calls and asks me if I had this problem while I had my "emergency lights" on? (Im on a fire department). I said no why. Their first instinct was to put blame on what they refer to as an "after market add-on". I said it was not the aftermarket addon. First off, they have been in for more than a year with no problems. Second, my whole light system is completely isolated from everything else. They then moved to my strobe cables saying it might be interfering with some computer box on the drivers side. I said, no try again. Strobe cables are shielded to prevent such a thing. Later on, they said it was 2 censors....if I can remember what they called them, I think a crank sensor, and a throttle position sensor? Make any sense? Something about they both monitor each other, and if they dont get the same reading, it pops that error message up and sets a code. Apparently they got a code but couldn't reproduce the problem. Looking at my receipt after I picked up my truck...it says:

 

 

Systematic Testing Code P2135

Replace Failed TBI Unit & Reprogram PCM

 

 

Again, I'm not a mechanic so I don't really have any idea what this is. Any help would be greatly appreciated :chevy: Have a great weekend!

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Code 2135 is Throttle/Pedal Pos Sensor/Switch A / B Voltage

Correlation

 

So sounds like they replace the TPS based on this code.

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Code 2135 is Throttle/Pedal Pos Sensor/Switch A / B Voltage

Correlation

 

So sounds like they replace the TPS based on this code.

 

<{POST_SNAPBACK}>

 

 

Any ideas what would cause this?

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Did the "Reduced engine power" message come on when you took your foot off the pedal after the 70-75 mph cruise?

 

Apparently there are two throttle position sensors near your gas pedal, A, and B. Actually they must be in the same module, but they apparently have independent electronics. Well apparently the output from A didn't agree with the output from B, so the code was set and the "reduced engine power" message was displayed, and your computer entered "limp" mode. Seems like overkill, to enter limp mode just because of the throttle position sensors being faulty... maybe they're keeping a fail safe on this because it's so highly critical that the throttle position sensor never malfunction in the sense that it applies more throttle than you were asking for. So if it's in doubt, limp mode ensures you could overcome the measly "reduced power mode" throttle with a light application of the brake.

 

I think your dealer's techs must have wondered how the position sensor failed, must be a rare event. That's why they were asking about your strobe.

 

Even if the strobe has shielded wiring all the way to the battery, it can still send spikes through your electrical system. Hypothetically speaking, I think a spike is one thing that could have fried half of your throttle position sensor.

Edited by mmmikkke

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Did the "Reduced engine power" message come on when you took your foot off the pedal after the 70-75 mph cruise?

 

Apparently there are two throttle position sensors near your gas pedal, A, and B.  Actually they must be in the same module, but they apparently have independent electronics.  Well apparently the output from A didn't agree with the output from B, so the code was set and the "reduced engine power" message was displayed, and your computer entered "limp" mode.  Seems like overkill, to enter limp mode just because of the throttle position sensors being faulty... maybe they're keeping a fail safe on this because it's so highly critical that the throttle position sensor never malfunction in the sense that it applies more throttle than you were asking for.  So if it's in doubt, limp mode ensures you could overcome the measly "reduced power mode" throttle with a light application of the brake.

 

I think your dealer's techs must have wondered how the position sensor failed, must be a rare event.  That's why they were asking about your strobe.

 

Even if the strobe has shielded wiring all the way to the battery, it can still send spikes through your electrical system.  Hypothetically speaking, I think a spike is one thing that could have fried half of your throttle position sensor.

 

<{POST_SNAPBACK}>

 

 

 

 

Even if its not even tied into anything else? And also...why just now? The strobes have been in there for over 6 months?

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It might be that your strobes didn't cause the problem. Heck, I have a strobe, and now this has me a wondering about mine. My strobe is wired to the snow plow prep roof lamp wiring. Mine's more likely to cause spikes than yours is.

 

If Whelen's strobes had a problem blowing out TPS sensors, it'd be on the internet by now. I checked; didn't find anything. I think you're ok.

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It might be that your strobes didn't cause the problem.  Heck, I have a strobe, and now this has me a wondering about mine.  My strobe is wired to the snow plow prep roof lamp wiring.  Mine's more likely to cause spikes than yours is.

 

If Whelen's strobes had a problem blowing out TPS sensors, it'd be on the internet by now.  I checked; didn't find anything.  I think you're ok.

 

 

 

Thanks for all the info. I've had strobes for years. I know they are grounded through the powerpack and whatnot. Just seemed kind of weird. Guess I'll see if it happens again. I do appreciate all the insight though, as always :chevy:

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