2005 Chevrolet TrailBlazer LT - Answered Questions & Fixed issues

Our Professional Auto-Electrics Technician Jeff Armer writes. Jul 03, 2023 Engine coolant fan circuit malfunction 1 ? What code P0*** what ? How do you know it needs a new fan clutch ? Before you go hacking up your wiring. Do you know how this fan clutch works ? Cooling Fan Control The purpose of the electro-viscous (EV) fan clutch is to maintain powertrain cooling requirements. The powertrain control module (PCM) monitors the following sensors to regulate the fan speed; • Engine coolant temperature sensor • A/C refrigerant pressure sensor • Vehicle speed sensor • Intake air temperature sensor • Transmission fluid temperature sensor • Ambient air temperature sensor The PCM controls the electro-viscous fan clutch engagement. The PCM regulates a 12-volt pulse width modulated signal (PWM) to the cooling fan relay. The PWM signal determines the ON time of the relay. As the commanded state of the fan clutch increases, so does the ON time of the relay. This ON time directly effects the amount of time the solenoid, which is internal to the fan clutch, is energized. When the solenoid in the fan clutch is energized, it opens the spring loaded valve and allows fluid to flow from the storage chamber to the fluid coupling of the cooling fan clutch, increasing the fan speed. When the solenoid is de-energized, the spring loaded valve closes, and blocks the path of the fluid to the fluid coupling of the fan clutch, reducing fan speed. The fan has the ability to create a feedback signal, so the PCM has an actual fan speed input. This is done with a hall effect sensor internal to the fan clutch. The PCM supplies a 5-volt reference and a low reference to the hall effect sensor. The hall effect sensor returns a signal pulse through the cooling fan speed signal circuit in response to the reluctor track passing by the magnetic field of the hall effect sensor. The PCM commands the cooling fan to 100% under the following conditions: • Engine coolant temperature exceeds approximately 129°C (264°F). • The transmission oil temperature exceeds approximately 151°C (304°F). • A/C refrigerant pressure exceeds 1655 kPa (240 psi). • When certain DTC's set. These include P0116, P0117, P0118, P0125, P1481, P1482, and P1484. The scan tool can engage the cooling fan clutch. This is done with the engine controls special function menu screen. To engage the cooling fan, It can take up to 2 minutes for a 100% command with the engine at 2000 RPM. The lower the engine speed, the longer it will take the fan to engage. To disengage the cooling fan, it can take up to 2 minutes with the engine at 2000 RPM. The lower the engine speed, the longer it will take to disengage. In lower ambient air temperatures the cooling fan will engage in less time, however, it will take longer to disengage due to the properties of the fluid vs. temperature. Under certain conditions the cooling fan may be engaged at engine restart. They are as follows; • The cooling fan was engaged at the time the engine was turned off • The fluid may bleed from the storage chamber into the fluid coupling of the cooling fan Although the fan is commanded off at this time due to a cold start condition. This is the most likely time a vehicle driver will notice that the fan noise is excessive compared to normal engine starts with out cooling fan engaged. As the engine speed is increased the fan noise will be louder than before. These are normal conditions that can be very intermittent. Do you know how many DTC'S this system can set an what they are for ? DTC P0480 DTC P0483 or P0493 DTC P0495 DTC P0526 DTC P1258 DTC P1481 DTC P1482 DTC P1484 DTC P0480 Cooling Fan Relay 1 Control Circuit ,this wouldn't have anything to do with a bad clutch fan. ==================================== Basically, you are attacking the problem the wrong way and your solution won't work. The answer is in the electronics and you need an auto electrician with a professional grade scan tool computer to scan for the analytical data which will dictate the fix. https://www.google.com/search?q=auto+electrician+near+me ..

My Haynes manual calls for 35 ft/lbs

Should be near the oil filter on the side of the block.

You have a stuck scity contr solenoid ..

the first thing you need to do is sc the truck see if you dont have any codes on the system to falow diagnostic on the problem

posible blower motor resistor relay 1 pieze located under globe box ner blower motor

In this video: http://www.carcarekiosk.com/video/2009_Chevrolet_Trailblazer_LT_4.2L_6_Cyl./fuse_interior/replace

If it is running fine live with it. Other wise I would check the mass air flow sensor maybe?

hi mate you should be able to remove handle ..if you remove the inner panal on thee inside of the tail gate...it sould be secured with i think 10 mm nuts ...you need to remove the linkages to be for you can remove the handle....to remove inner panel it should just be cliped in place use a butter knife and slide it in the gap around outer edge of the panal.and gently pry the panal away from the tailgate..

Because the computer was reset after battery change, and you probably need to have the throttle body cleaned. It grimes up often and needs to be cleaned every 10 - 15K miles.

check your blower resistor it should have three to five wires to it and located close to the blower motor

Wheel bearing or CV joint?

Blend door actuator

my TB did the same thing and I took off the ThrottleBody and took a rag with a can of Throttle/Carb cleaner and clean the ThrottleBody real good.....You will need some type of brush like a toothbrush to scrub of some of the old buildup of carbon.....my TB runs fine now....

You will need a brake light switchlocated at the brake pedal

all fuses all boxes checked. cab and engine bay? well we scan all modern cars first./ it will show DTC errors. like dead cluster communications? or? do not skip scans on cars, or go broke guessing endlessly.for sure.

to 12 year late jackers why not just check them all. be faster. or read the manual lost the glove box users guide,chapter fuses? its free. https://eautorepair.net/Marketing/Default.asp

I did some testing, fuel pump was bad but not the problem. Turns out I had a bad power train relay. I jumped it and it fired right up and ran at idle smother than it has in a long time

NO CAR year TOLD AT ALL HYJACKER. TO 2009 AND SAME PROBLEM WITH lJBDJ \Chevrolet TrailBlazer some cars have FLAP that only protects fill nozzle from cracking body paint. so is not at all part of EVAP buy a new cap. if still fails buy the tank filler assembly from chevy, parts. nobody can see your flap , no posted photo of it, and matters hug.

right hand side of the engine looking at vehicle from Hood has a little tiny vacuum line coming from plenum to fuel pressure regulator regulator has hard steel lines connected to it leading to firewall if this doesn't help Google year make model and regulator