i wouldn't need to connect the R/O from the EATC that goes to the relay to the R/O in the truck harness for any reason would i?

 

anyone?

 

Dual function. In the stock non-EATC wiring, The red/orange is a switchable wire that can supply ground to the blower relay coil and provide ground for the blower motor itself. After the mod, it is used only to provide ground for the relay coil. That's why it is connected to the yellow/black at the EATC HU.



Not with a 99 HU.



No.

 

shoot....i am at a loss.......i guess i will be looking for a new HU and try that....maybe that is the problem......after the HU is powered off, the Y/BLK wire has somewere of 1.5v going through it.....

 

That's close to ground level, so you've got about 10~11 volts across the blower relay, more than enough to activate it.

I've never measured it but I would guess that the yellow/black should be near 0V when the EATC is on and jump up to about 12~13V when the EATC is off.

The yellow/black (HU pin 17) and the red/orange in the 97 dash harness:

• Are they connected together?
• Are you absolutely sure that they are NOT connected to anything except the EATC HU and the blower motor relay in the underhood box?

 

they are connected together at the EATC, and unless the R/O is connected somewhere else in the factory harness then that would be my guess as to they are only connected at those 2 points......it isn't connected to anything at the FSC, just got a butt connector and some tape on that end....

whenever i disconnect the R/O wire and the Y/BLK wire, the fan doesn't blow at all....

 

That's because the blower relay coil loses its ground and opens the circuit to the blower motor.

 

you don't happen to know if the R/O wire goes anywhere in the factory harness do you?

so should i try and connect the R/O wire somewhere else?

 

i wonder if i take the ground from the FSC and hook it to the R/O wire under the hood if that would work....

 

No, you don't want it connected anywhere else. In the factory harness, it goes to the blower relay coil, the blower resistor and the HVAC control panel. You disconnected it from the resistor assembly, so now it should be running between the EATC HU and the relay coil - that's what you want.


No, that won't work. Trying random combinations won't help and it has the potential of letting the smoke out of the electronics ... or worse.

 

alright....my last option is a bad HU i guess......looks like i am off to find a new 1

 

i wonder if i ran a new wire for the B/O wire from the cab to the FSC and took the B/O off the O/BLK wire at the FSC if that would work?

something like this:
B/O (HU) --> B/O (FSC)
O/BLK (FSC) --> O/BLK (Fan)

with them not tied together at the HU nor the FSC....

 

Yes, the brown/orange must run between the FSC and the HU and nowhere else.

Yes, the orange/black from the blower motor must run to the FSC and nowhere else. The branch of the orange/black that runs into the interior should be electrically disconnected from the wire that runs between the motor and the FSC.

Bases on your previous posts, I thought that's how these were wired already.

 

no i am sorry...i have currently the B/O wire tied into the O/BLK wire at the HU and the same way at the FSC per John Grigg's How-To (or that is how i read it....)(so i wonder if i spent $75 for nothing.......)

now that i go back and re-read after what you just said Bob, i see were it talks about that! i bet that is my problem! I will try and correct the problem when i get home from work!

i wonder if changing that will fix the a/c not working also hummmmmm

 

That's OK as long as:

(1) you are simply using the truck's orange/black in the harness as an "extension cord" to get from the FSC brown/orange to the HU's brown/orange;

and

(2) There is no electrical connection between any wire in (1) with the wire that runs between the FSC orange/black and the blower motor orange/black.

 

sweet! right there is my problem! i have the B/O wire at the FSC tied into the O/BLK wire that goes to the fan O/BLK wire! i will take it out of that connection and put it in the O/BLK wire that goes into the cab! man i can't believe that it was that simple i feel like a freakin idiot now.....

 

Cool, I hope that's it!

 

yea me too!

 

got her all fixed now! stupid me! don't know how to read! i will post pictures tomorrow....

 

does this mean i don't have to go digging thru my garage to find my hu??

good job gettin yours fixed!

 

Anyone post a satisfaction number for this mod, 1-10 and then post a difficult wiring number 1-10. 1 being the least satisfied, least wiring, 10 being the most satisfying and hardest wiring. I am thinking about doing it, just don't want to drop the money on something I'm not going to enjoy. Also, post an average price for the stuff that you paid total!

 

yes this means you don't have to dig through your garage!

 

Satisfaction = 10
wiring = 7 or 8

it isn't really that hard.........just pay attention to the how-to.........

 

Glad to hear you got it working. I'm interested to see the pics, as well

And a salute also is due Bob for helping you get back on the track.

 

Amen it's working :)

For me, satisfaction: 10

Difficulty: 8-9