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Discussion Starter #1
I had a friend help me put a new machined cyclinder head and Timing chain in my trailblazer 4.2l. Also new water pump, plugs, fuel pump, fuel injectors, coils. After go it running fix the p0300 got two bad coils replaced them. The engine idles great and when press the gas pedal to increase rpm it seems to skip just lightly taking the rpms up.

But when I drive it take it very slow it will go to 30 mph but if I press on the gas it will die and give codes P2135 and P0651. I reset the codes and today went to start it and it died and gave the same codes. Did not reset the codes yet but now I can start it and it will idle without issue. I fled it 20 minutes no over heats or oil pressure issues.

Any ideas what the fix could be? Was told the throddle body or the car pedal sensor maybe but on a low budget not sure how to test them I have a old cheesy code reader about the years old.

Appreciate any help I need this vehicle to drive to the cancer treatment center so my wife does not have to take off work and drive me. Thank you
 

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2004 gmc envoy_slt
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The P0651 refers to the 5V reference voltage being missing. This reference voltage is used by the throttle body and fan clutch. A good place to start looking is the wire harness going to the fan clutch. Sometimes the wires can be abraded and short out. If this is not the problem, more troubleshooting would be required.
 

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Discussion Starter #3
The P0651 refers to the 5V reference voltage being missing. This reference voltage is used by the throttle body and fan clutch. A good place to start looking is the wire harness going to the fan clutch. Sometimes the wires can be abraded and short out. If this is not the problem, more troubleshooting would be required.
I will have to check it this weekend or Friday with my friends help. Got the chemo treatment sickness which sucks.

I'll post what we figure out.

Thank you for the help and response.
 

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Discussion Starter #4 (Edited)
05 Chevy Trailblazer 4.2L continued saga

05 trailblazer 4.2L EXt
New - Plugs
New - Coils
New - Fuel Injectors
New - Fuel Pump
New - Fuel Pump pressure Sensor
New - Water Pump
New - Timing Chain
Re-machined - Cylinder head with new values, springs and rocker arms
New- Seals, head gaskets, exhaust manifold gasket, intake manifold gaskets.all seals plus etc.
New - Oil pump
New - belt
New - map sensor

- Was getting a P2135 and P0651 Due to my low budget and my cancer treatment I went to the junk yard got a used throttle body form 05 trailblazer with 86K that was a rollover wreck for $22.

Now the vehicle runs better but if I press the pedal down to give it gas for a fast acceleration from 20 mph to 50 mph if hesitates 3 - 4 times but will get up to speed. Never took it on the highway yet so 50 mhp is the max speed I tested.

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Should I change the gas pedal sensor also?
The electric fan clutch must be working OK never over heated in 96 Degree F outside temperature driving for 30 minutes.

I know the gas pedal, throttle body, and electric fan clutch and maybe the gas tank pressure sensor all run on the the 5 volt agree and disagree reference.

Also disconnected the tail pipe in front of the catalytic converter still no change just more noise :)

Currently throwing no error codes at all and engine light stays off?

Any suggestion to try next? Or test?


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UPDATE:
I went out to the trailblazer to get a my manual and tried to start it.

Would not start and throw a P2136 P651 P2135 codes. Cleared the codes.


Just wondering I decided to unplug the electric fan clutch. The trailblazer started and throw the P0651 code which I know it would.

This is the voltage B ref per my cheap old reader.

Could this be caused be the fan clutch and still cool the vehicle in 97 F heat?
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Thank you in advance!
 

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Discussion Starter #5
Ordered water pump and fan clutch parts

I ordered a new fan clutch and water pump should be here Sept 2nd for the 05 Trailblazer 4.2l. I order parts online because driving an hour one way to the nearest parts store sucks.

Been having a weird whining noise that goes away after about 5 minutes thought it was the belt and after I took the belt off the and turn the water pump bell pulley it makes the weird sound but only when I turn it counter clock wise. Never seen that happen before???

Changed the throttle body it's running better but low power and hesitates acceleration. Running out of marts to replace maybe I should do a parts cannon and replace the rest have a completely new engine. Sad thing I really like the trailblazer. :)
 

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2006 Chevrolet Trailblazer LS
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smashed pins

You're shooting an awful amount of parts. Check the wiring harness where the fan clutch plugs into the main harness at the radiator. It's very easy to smash one of those pins and cause a bad/no connection (been there.:bonk::bonk:).
 

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Discussion Starter #7 (Edited)
Victory It's running!

I did check all the wiring connectors, fan clutch, coils, map sensor, throttle body, VVT sensor, camshaft potion sensor, both O2 sensors and gas pedal connectors they were all OK before buying the fan clutch and water pump.

It was the electric fan clutch installed a new one plus new water pump and now it runs great cross my finger it stays that way.


Yes, I did a parts cannon :bonk: on it but still cheaper than a car payment since it's paid off. If I get another 60,000 miles or more out of it I will be happy and the body and inside are like new except for the plastic trim sun faded.

Cheap but nice looking vehicle to get me to my cancer treatments perfect for me.

Thank you everyone for your feedback and help it's greatly appreciated and helped me a lot!

God bless!
 
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