1999 Blazer LT 4.3L 4x4 Mileage: 130k
This forum is to let all you Blazer fans with a freak find. Took me hours to find Diagrams and other forums kept me with run around. YouTube doesn't share detailed diag. Plainly, I had burnt wires from my dashboard harness to the body harness. Completely gutted ol girl down to metal from Dash board pulled to steering column removal. 4x4 kept blowing fuses that led to my IPC to show nothing. I performed a cluster sweep test to eliminate that IPC was an issue. OHM wiring from 4x4 switch PRP/WHT to Transfer Case Control Module 1.0 ohm then started back probing everything and got .5 ohms elsewhere. GRN wire which was a Signal for ECT (Engine Cooling Temp) and Fuel from IPC to PCM was 1.0 ohms. Eventually, started removing the dash and found the horror.
Anyways, 7mm LH fuse box panel. Turn it backwards and inspect wiring. Mine was a brown wire, I dont recall fuse number. Extensive damage to wiring which no junkyard around my way has one and I am too afraid to throw a 99 GMC Jimmy 4x4 harness because of potential Pin Relocation. Looks like I'm depinning and rebuilding both Dashboard and Body wire harness. Amazon has pins both Female/Male. I believe it's a 1MM for these either 16 or 18AWG. Haven't started the repair. Just performed teardown.
Also failed to mention. $350 Used on Ebay for Dashboard Harness. Body harness is nowhere to be found where I'm from. Yea, not spending that when a junkyard would cost only $150 for both Dash and Body harness... Repair on my end it is. Electrical work...Yay!
Freak issue. Thought I'd share. Wish it was an Engine or computer PCM or BCM fault smh... I'd rather do an engine rebuild tbh. All advice welcome and/or constructive criticsm.

 

Yikes, what a "cluster". Make sure to use same wire gauge or thicker, hone your soldering skills until you can get clean shiny joints and use heat shrink tubing on the fixes. Pretinned stranded wire will be easier to solder. If you have some stubborn wire corrosion and you cant cut back any further, some additional liquid flux may get you a good solder joint.

George

 

I appreciate your input. My thoughts exactly. 16 awg wire. Although, thinking about using the heatshrink with solder and double insulating the repaired wires with heatshrink sleeves to keep moisture out in case of repeat issues. Unknown source of condensation and or corrosion. However, thinking it was coming from the heater core insulator from exterior to interior. Leaks when it rains aparrently. The trickle down made sense since the Heater Core is out and its been raining these past few days and came from that very portion on the firewall hole. Just a theory. Haven't gotten into details with it yet nor have I thoroughly inspected my removed components. But since I'm halfway there, fiest, repair all wiring. Replace Heater Core. Evaporator and Orifice Tube is almost there cause RF Fender Liner is out for the removal of the Heater Core HVAC box secured by stupid 2 lower and one mid (in the Evap box) mounting bolts... brake light switch... why not. Practically a brand new SUV. Shifter cable grommets are still in tact surprisingly. I'm droning and dreading. Overthinking and ready to tackle it. Again, felt like sharing. ADHD took over.
I was speaking with my colleagues and they suggested to still yank the 99 Jimmy Dashboard harness to 1) Speed up the process and 2) Referenced that the Jimmy harness is the same according to a source working at the Chevy dealer. Funny thing is, I did not know that this is actually a common issue. Well again... haven't started the repair but I'll be glad once it's back on the road. I have showed a number of techs that knows quite a bit and quite a few said they would run away from this lol. Even though, after hours everyone calls me... Putting my experience to the test. Second time rebuilding a harness... So much faith in me. I'm just a humble mechanic that plays with legos... time to make sense of this spaghetti madness.
Anyone who reads this post, I'll be sure to give you a progress update when I meet my personal deadline by the end of the month. Need the time and obviously cant rush it. Hold my beer and watch this! Wish I could summon a Shadow Clone Jutsu! Hehehe Bzzzt. Electrical... yay!

 

Common sources for the water are:

1. Heater core
2. leaking windshield
3. sagging door due to hinge bushings
4. rusted floor pan

Good luck.


George

 

Heater core: Potential
Leaking windshield: Potential
Sagging door due to hinge bushings: Very Likely. Recently Repaired Both Door hinges and Moldings
Rusted floor pan: Undergoing Inspection. Unlikely
>Making me feel like you've done this before George! Thank you

 

Breakdown. Finally soldered and connected after days in and beers plentiful. Electrical Poetic Dream! Individually depinning both Body Harness and Dashboard Harness with Donor Harness from a 99 Jimmy color coded and all.... Finally started. No CEL, although one hiccup. My Blend Door Actuator is not responding. I have 2 connectors. One insulated and one just electrical taped. Both connectors fit the Blend Door Actuator.
I lost myself in time. No extra bolts, thank God! Mrs was breathing down my neck. I replaced the Heater Core, why not. Already there. Connected everything but the two that fits the Actuator. Found out that this Blazer has Automatic so everything is more costly than a Manual Temp.
Blower Motor has a spade connector, currently researching Diagrams to see if I can just use a bolted Spade Connector for Blower Motor... found one on Rock Auto. AC Delco OEM. Prolly going to stick with this. Sick of cut and splice, solder and insulate... bottom line. Initial issue is fixed. We have 4WD again! I don't k ow what I'm doing. This is my first time lol.
Customer States is repaired.
Update: Rebuilt Harnesses. Correct Pinset
Update.-New Heater Core New Evaporator -New White Orifice Tube .
Ongoing: Blower Motor with Spade Connector and Blend Door Actuator Pin 12456., Battery, Door Jamb Moldings, and Over Engineering Silicone Everything.
Further: Emissions, Tags, 5 Tires, Alignment. Merry Xmas Mrs!
Cluster Gauges are now operational... Fuel, Coolant Temp, Trans Range Selection.

 

Wow! Great job!!

Smart move to replace heater core.

Regarding the blend door actuatoactuatod it be bad? These can fail due to the gears in them cracking and then the gear axles no longer being connected to the gear.

I have a 99 service manual. If you need schematics, let me know.