Why? Jumper from blower to resistor?

[Badkitty795]

Hi! I'm new here. I'm a mom and I'm fixing up an 04 Envoy XL 4.2 for my son. I've done some minor wrenching in the past, but I'm using this one to teach myself some more in depth skills. I won't go into some of the other questionable choices made by previous owners on this post so I can keep it more to the point.

After some more major repairs, I decided to tinker with why the blower motor wasn't working. Umm. I found this.. Naturally, I'm going to test some things, but I'm curious as to what someone would have been trying to accomplish by stripping insulation on the power wire to the resistor and attaching this green wire. I don't know what the other end was connected to because it fell off when I pulled on it.. insights?

 

[Mooseman]

My guess is he had a blown resistor and bypassed it to connect to the blower motor directly. Pretty sketch in any case.

 

[Badkitty795]

That's kind of where I was going with it. And sketchy is the name of the game with whomever tinkered with this girl in the past. Don't get me started on what we found when we were replacing the transmission this week! Resistor was definitely bad. Confirmed with volt meter. Replaced, but blower still won't come on. Moved another 40 amp fuse to the blower motor spot in the fuse block under the hood. Still nothing. Neither rear or front come on. On the upside, the compressor seems to be coming on. Any suggestions would be appreciated.

 

[Blckshdw]

Check fuses 36, 39 and 44 in the rear seat fuse block as well. 44 is the line that feeds power to the blower via the control module in the dash. I had been chasing an intermittent blower power issue in my TB EXT and turns out that the wire between the rear fuse block and the control module may be pinched. I haven't fixed it yet...

 

[Badkitty795]

Check fuses 36, 39 and 44 in the rear seat fuse block as well. 44 is the line that feeds power to the blower via the control module in the dash. I had been chasing an intermittent blower power issue in my TB EXT and turns out that the wire between the rear fuse block and the control module may be pinched. I haven't fixed it yet...

I will do that when I get home from work in the morning. Thanks!

 

[azswiss]

Moved another 40 amp fuse to the blower motor spot in the fuse block under the hood. Still nothing.

Based on the sketchy, and downright sloppy, job done by the previous owner/tinkerer I would be really suspicious that there are additional mods that were made between the blower and the fuse block. Looks like this is going to be a trust but verify situation; you are going to have to confirm everything between the fuse blocks up to the connectors against the schematics.

 

[Badkitty795]

Based on the sketchy, and downright sloppy, job done by the previous owner/tinkerer I would be really suspicious that there are additional mods that were made between the blower and the fuse block. Looks like this is going to be a trust but verify situation; you are going to have to confirm everything between the fuse blocks up to the connectors against the schematics.

I think so too. They pulled up the center console for some reason because it's still not bolted down properly, so I'm going to pull that up too. There was some weirdness in the fuse block when I first got it. Several fuses were in the wrong spots and there was an extra on the row with the blower and ignition fuses and one of the ignition fuses was the wrong size. (see pic). I have most of that straightened out now, but any insight as to what they may have been trying to bypass/rig would be appreciated so that I can fix it properly.

This truck does have good bones. I bought it from some very good friends. Her recently deceased dad had a car hoarde and this was one of them, so background isn't known. The engine is in great shape, very healthy. And fortunately, very little evidence of rodent rewiring on the outside and no rodent residences on the inside. Thankfully, the past people seem to have stayed out of the engine bay.

I just replaced the fuel rail and the injectors (that was a job!) and with some help from my friend I bought the car from (son in law of the car hoarder) and my dad, put in a new transmission this week. (The car hoarder paid someone to put a junkyard transmission in and one little detail to tell you the quality of the work they did.. the shift lever was installed backwards on the manual shaft)

Sorry for the side note/long post there.. it'll take just a bit more work and patience, but she's gonna be a great truck for my son.

 

[azswiss]

There was some weirdness in the fuse block when I first got it. Several fuses were in the wrong spots and there was an extra on the row with the blower and ignition fuses and one of the ignition fuses was the wrong size.

Wow! I would definitely want to know what the underside of the fuse block looks like. I would be looking for anything out of the ordinary such as: odd splices (location, wire gauge, colors, etc.), open or damaged sections of wire loom, anything with black tape dangling off it, exposed wires. Good luck!

 

[Badkitty795]

Wow! I would definitely want to know what the underside of the fuse block looks like. I would be looking for anything out of the ordinary such as: odd splices (location, wire gauge, colors, etc.), open or damaged sections of wire loom, anything with black tape dangling off it, exposed wires. Good luck!

So far what's coming out of the fuse block looks normal. I had my face in it for extended periods of time while I was getting the intake manifold off, but I think a more careful examination is warranted for sure.

 

[Badkitty795]

So.. This is my new theory based on evidence at hand. Someone spilled a soda on the dash which blew this wire in the harness to the resistor (gooey brown yuck on the inside of the glove box was also still on parts of the wire harness). Dude or dudette 'rewired' it splicing a new wire from resistor power wire to harness (there is literally melted plastic from the slice wire on the connector). A somewhat ineffective repair, to say the least. I'm going to the pull it yard Monday. I'll add this connector and, for good measure, a blower motor, to my list. All the fuses in front and rear checked good. And I haven't found any more sketchy wiring... Yet.

 

[Badkitty795]

So. I went to a pull it yard for the first time, by myself, and with my $25 coupon, got a pigtail, blower motor, kick plate and tail light for $8.00. Drove home sweaty, yet victorious. Installed and wired in my spoils and got.. bupkis. No rear blowing, no front blowing. I had a talk with Louise the Envoy about how she can trust me. I won't hurt her like other people have. Somehow I don't think she's convinced.

I checked my new pigtail with a test light per the service manual procedure and the red wire lit up, but none of the blower speed wires did when the appropriate speed was selected on the dial. I'm starting to think it may be the hvac module. I pulled it out and saw no obvious issues. I would like to test it with a multimeter, but that gadget remains largely a mystery to me. Does anyone know how to test the module for continuity aka does it work-ness using a multimeter? Does this question need to be posted on a new thread? Any help is appreciated.

In other news, Ms. Louise came down off her blocks and we took a spin around the block this morning after I got off work. This was the first time I've actually driven her since we bought her in February. After a fuel rail, injector replacement and putting in a rebuilt transmission (a friend and my dad helped me put in the transmission), this was definitely a victory lap. A hot lap (as in geeeeez it's hot with no climate control), but a victory lap nonetheless. The major repairs are done, and though she still has a ways to go, I'm determined to save her.

 

[Mooseman]

Using a test light or the multimeter, check what voltage is coming from the HVAC module to each terminal going into the resistor pack. If that is 0 from all, then check the voltage going into the HVAC module according to the schematic.

 

[mrrsm]

Welcome to GMT Nation...

You've probably already thought about this... But jik not... FWIW... Have another look at your Photos for:

(1) The presence of A Uniform Line of RUST on all Ferrous Metal Surfaces; especially around the entire outer base of the Plated Blower Motor Shell Casing and on the adjacent surfaces of the Body and Door Hinges.

(2) The presence of "The Mysterious Brown Mung" (Lake Bottom Goo?) you found mashed in between the Plastic Dashboard Fascia segments.

(3) The presence of the Green Cupric (Copper Oxide) Residue inside of ALL of the Plug Wires Contacts inside of the Blower Motor Connector.

(4) The Badly Rusted and Corroded Fastener holding the Rusted Ground Strap Tang to the Mega-Fuse as shown in your Fuse Box Image.

All of these conditions Add Up to imply that the Prior Owner of this SUV was either trying to get a Certification as a "U-Boat Commander" ...or at some time in its life, THIS Vehicle was partially submerged during a FLOOD... and then 'Steeped in it's Own Juices' for quite a while afterwards.

These conditions might explain the difficulties with sorting out THE Most Important Element of ALL for establishing Good Electrical Circuits:

Obtaining Good Grounds.

THIS Thread from @Realism will prove very Helpful in Finding, Cleaning and Re-Attaching ALL of the Ground Connections for the GMT360 Vehicles (with just a Small Dollop of Dielectric Grease added in between the contacts to prevent further Galvanic Corrosion).

Electrical Ground locations

While troubleshooting a bad ground I came across some scans of the service manual regarding electrical ground locations for our platform posted on another site. This includes both short and long wheel base, as well as both 4.2L and 5.3L. Credit goes to Wex...

gmtnation.com

One Other Suggestion...

If the Fuse Box Cover is Missing... it will be a Good idea to get a Can of "Canned Air" and after blowing out all of the surface dirt and sand covering the Fuse Box... Pull One Fuse at Time... and do likewise... while looking for any signs of Friction and Vibration Wear on the Plug In Tangs or any Corrosion.

Replace ALL of the Fuses if you find ANY in Very Obvious Poor Condition. The Cost of an entire Automotive Fuse Kit sufficient to fill all of those Fuse Slots is around $15.00 - $30.00 over on Amazon.

Replacement Fuse Box Inner and Outer Covers are abundantly available over on eBay; likewise, For Not Too Much 'Moolah' :

trailblazer fuse box cover for sale | eBay

Get the best deals for trailblazer fuse box cover at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!

www.ebay.com

With your Strong Desire to Learn New Things about Automotive Diagnostics, Visit THIS Video on "Multi-Meter Basics" from Paul "Scanner" Danner for some Excellent (FREE) Professional Training that will be very easy to absorb and apply to your need for using a Lighted Probe for Testing Loaded Circuits on your son's SUV and for How To Use a Digital Multi-Meter (DMM) or a Digital Volt Ohm Meter (DVOM) :

THIS Video provides a COMPLETE Free *** Professional Automotive Course on Intermittent Electrical Problems (which incidentally... covers the REASONS for the Failure you discovered with your HVAC Blower Connector) and so much more:

*** Please Forgive the "Fellahs" designation the 'Old School Instructor' made towards the attending Class Members. Solving Automotive Diagnostic Problems should never be qualified or responses provided based upon a Person's Gender.