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docckingg
docckingg, ASE Certified Technician
Category: Chevy
Satisfied Customers: 37
Experience:  GM Master tech, Cadillac Master, ASE Master tech, 25 years EXP
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Trailblazer: electrical issues..ign..the HVAC resistor but the problem

Customer Question

I have an 04 Trailblazer with electrical issues. I have replaced the ign sw 3 times. now I am having HVAC problems, Replaced the HVAC resistor but the problem still there. HVAC fan in position 1,2,3 or 4 will cause Anti-lock brake, Brake and Service 4wd warning lights and audible warning to come on. Fan in position 5 or OFF, no lights or warnings. Fan will only work in pos 5. Is this a common problem with the Ing sw or might it be in the HVAC fan control? or something else?
Submitted: 5 years ago.
Category: Chevy
Expert:  docckingg replied 5 years ago.
Stan,,, Whenever i have problems like this the first thing I check are the grounds. If you need to know where they are let me know
Customer: replied 5 years ago.
Checking the battery voltage and all the grounds was the first thing I did prior to replacing any of the components. Even the ground located under the center console.
From this info what might cause this issue?
Expert:  docckingg replied 5 years ago.
04-08-45-010: Various Interior Electrical Concerns, IP Gauges/Lighting Inoperative, HVAC Controls Inoperative, Blower Motor Inoperative, Radio Inoperative, Flasher Inoperative (Repair Ground 201) - (Sep 24, 2004)

Subject:Various Interior Electrical Concerns, IP Gauges/Lighting Inoperative, HVAC Controls Inoperative, Blower Motor Inoperative, Radio Inoperative, Flasher Inoperative (Repair Ground 201)

Models:2004-2005 Buick Rainier
2002-2005 Chevrolet TrailBlazer, TrailBlazer EXT
2002-2005 GMC Envoy, Envoy XL
2004-2005 GMC Envoy XUV
2002-2003 Oldsmobile Bravada

 



Condition

Some customers may comment on intermittent operation of various electrical components in the interior of the vehicle. Components that can be affected are not limited to the list that follows:

IP Gauges/Lighting Inoperative
HVAC Controls Inoperative
Blower Motor Inoperative
Radio Inoperative
Flashers Inoperative
Transfer Case Shift Controls Inoperative

Service information ground distribution schematics should be reviewed for complete detail of items grounded at G201.

Cause

The cause of these conditions may be a loose or ineffective connection at ground splice pack G201 located on the right side of the front console area.

Correction

Repair the ground splice pack G201 connection using the procedure listed below.

  1. Remove the center floor console. Refer to the Console Replacement procedure in the Instrument Panel and Console sub-section of the Service Manual (SI Document ID #741894).
  2. Remove the 4 screws that retain the instrument panel (IP) lower closeout carpet panel to the IP substrate.
  3. Remove the IP lower closeout carpet panel.
  4. Remove the ground splice pack G201 bolt. If the bolt shows any sign of discoloration, clean the bolt using a wire brush.
  5. Remove any carpet that may have been trapped during assembly. Clean the ground surface on the body using an emery cloth.
  6. Install the IP lower closeout carpet panel.
  7. Install the 4 screws that retain the IP lower closeout carpet panel to the IP substrate.
  8. Install the center floor console. Refer to the Console Replacement procedure in the Instrument Panel and Console sub-section of the Service Manual (SI Document ID #741894
Expert:  docckingg replied 5 years ago.
check this ground if you havent already. I will keep looking for more info.
Customer: replied 5 years ago.
This is the ground that I checked specificly per local Chevy dealer recomendations. I will go back and check for a broken ground wire or connector.
Per the HVAC schematic I see there are 2 more grounds assocated with the HVAC control module G102 and G103(coolant bypass valve). Where might those grounds be located so I can confirm whether or not I checked them?
Expert:  docckingg replied 5 years ago.
Good job,,, Ok G102 is located rear of the underhood fuse block, G103 is rightside of engine compartment above coolant reservoir.. Also check G303 on the lower B-pillar and ground G404 on the outside of the frame rail behind the transmission cross member.
Customer: replied 5 years ago.
Not knowing the identifiers for the grounds, the ones you stated have already been checked and cleaned. I did check for broken wires at G201 bolt and block,w/Ohm meeter, I cleaned all the contacts within the ground block as well.
One more thing that I noticed, While driving, cruise control ON with the fan in position 5 and blowing, If I push (ON) the rear seat HVAC button, the cruise control will shut down.
I am suspecting this is not a ground problem but maybe another ignition switch failure. Or an HVAC control module internal problem. What do you think? I'll check back tomorrow morning.
Expert:  docckingg replied 5 years ago.
Normal ignition switch failures show up with transmission codes set and no starts, plus comunication codes as well. Maybe we have a voltage drop feeding the BCM or a bad BCM. The ground splice pack maybe grouned good but the circut feeding the affected circut could still be bad. Make sure all contacts inside the splice pack are ok. If all this checks good I would really need some scanner information from a good scanner to diagnose the problem. You have done a great job
Customer: replied 5 years ago.
Sorry I did not get back to you. I had to go on company travel and was out a couple of days.
I do not have my electrical schematics with me today, The BCM, I am assuming this a some type of Control Module, please specify what type and where located so I can check for voltage drop as you recomended.

I hope we are getting close to solving this problem, I'd love to go into my local Chevy dealer and tell their technitions what the problem was.
I'd accept your answers but I feel we have not found the cause of my specific electrical problem yet. I am confident that we'll get there and you will be paid.
Expert:  docckingg replied 5 years ago.
The connector on the blower motor resistor has been checked for good contact and no melting of the connector?? the bcm is a body control module under the back seat but lets not go there right now. Check the HVAC fuse number one for voltage drop. and check HVAC fuse B for voltage drop under load. I need to know what codes are stored for the ABS and any BCM codes. do you have access to a scanner that can do that? With problems in several different area's like ABS,HVAC, Cruise control I really am thing power and ground issues but maybe there are multible problems. Again we need to know what codes are stored
Customer: replied 5 years ago.
<p>Ok, As noted in the original question I replaced the HVAC (blower) Resistor. Coninuity was checked and there was no sign of over heating or melting around the old resistor or the connector or wires. as well as the new resistor.</p><p> </p><p> </p><p>As for codes. I do not have a scanner. But the original diagnostic at the Chevy dealer the tech said that no codes had been stored. We reprogramed the computers and reset the codes. and still no codes had been stored.</p><p> </p><p> I will check the voltage at the fuses' no load and under load. and get back to you on my findings.</p><p>Stan</p>

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