The infamous reduced engine power issue! - Please help!


Original poster
Jul 11, 2012
Here we go!
My wife has an '02 TB LT with the 4.2L I-6 Engine. It has 125,000 miles on it. We bought it new in February 2002. I have replaced the fan clutch 5 times since we bought it. Each would last about 1.5 years on average.
Over the past year and a half, it keeps getting the Reduced Engine Power light which in turn makes the SES light come on. It looses almost all of its power. If you pull to the side of the road and turn it off and then back on the REP light will clear and it will run fine. When it first started doing this it was very intermittent but now it is almost daily. I have had 4 aftermarket gas pedals installed. Each would last anywhere from 1 week to a month or so. The last time I replaced it with a GM pedal with the same results as the aftermarket brand.
I have replaced the throttlebody with a used one from a your pull-it yard. I cleaned it very well with throttlebody cleaner before installation. The issue was not seen for a week or two. I then replaced the PCM and had it reprogrammed. That worked for about a month!
I recently looked at the wiring harness to the throttlebody and even replaced the connector with a new one. I have not looked at the wiring harness for the fan clutch but will do that this weekend.

BTW, each time it goes into REP, it throws a P1271 code.

So, in summary I have replaced:
fan clutch = 5 times
gas pedal = 5 times
throttle body with a used one (but clean) = 1 time
PCM and had it reprogrammed = 1 time
connector on the throttlebody = 1 time
visually inspected the throttlebody wiring harness = 1 time

Does anyone have any other suggestions? I'm thinking a gallon of gas and a match! My wife is thinking a foot in my butt! Please help! Thanks!!


Dec 4, 2011
Do u know what the code means?? If not....


Original poster
Jul 11, 2012
Thanks jrSS!
I did know, I probably should have put it in my original post.

I have ordered the wiring harness connector for the gas pedal. I will replace it when it comes in and I will post the results.


Lifetime VIP Donor
Nov 19, 2011
Portland, OR
Is there any consistency to the position of the gas pedal when the issue happens?

Have you been able to put a voltmeter on the 5V reference voltage that's shared by the fan clutch, throttle body and the gas pedal to see if it's stable or has a glitch?

Inspected the harness near the PCM and all the places it goes that may be out of sight, where the wiring insulation might be compromised by rubbing on some metal?


Feb 26, 2012
Last time I got that light on was my 4th fan clutch about 2 hours from home, during work, on a sunday. Luckily the fan clutch grabbed the harness and shredded/shorted some of the wires together. Tape them up and all was well again. If you've done the fan clutch a bunch I would check that wiring as well.


Original poster
Jul 11, 2012
The Roadie, there is not really any consistency in the position of the accelerator pedal when it goes into reduced engine power mode. Sometimes it happens when you are driving other times it may be in neutral but running whenit does it. It does happen more often when the air conditioning or defroster is running but on the other hand it has done it without the either running.
Where is the common point where I would need to connect my meter to observe the 5VDC Reference Voltage that is shared by the TPS, APP, and Fan Clutch?
I will also inspect the entire harnesses for each. Especially, the fan clutch!

MMIN, thanks for the suggestions! I will post the results once I get all this completed. Hopefully, I can get it knocked out at least by the end of the weekend. BTW, I see that you are probably an expert on changing fan clutches too!!

Does anyone know where I can get some decent wiring diagrams that shows the actual contact/terminal numbers?

My Haynes Repair Manual does not have the wiring diagrams that I need. Even if it did; it isn't detailed enough to show the connection points.

Thanks in advance!

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