Dec. 15, 2011
My truck is a '98 4.3L S10 ZR2 that had no overhead console (referred to as OHC from here on).
I should also state that this was all done while my dash was out making wiring much easier.
When researching this, I couldn't find any real info on how to mount this whole thing. Wiring info was easy to find, but no one seemed to want to post their mount.
I found my OHC on eBay. It was the right color, had the HomeLink, and had the MODE computer. There are two computers available: MODE and ON/OFF. The ON/OFF only has a compass and temperature (less wiring too). The MODE has average MPG, instant MPG, fuel range, gallons used, distance to empty, along with the compass and temperature.
There are also 2 OHC's available: long and short. The long version (which I installed) has everything self contained in the OHC and has areas for sunglasses storage and a spot for CD's (I think that's what's it is meant for). The short version has no storage areas, either has or doesn't have the HomeLink, and also requires an extra mounting bracket. On this mounting bracket is an arm that holds the compass sensor. Make sure you get this bracket if you want the short version. I have no idea why the compass is separate since the computer in both consoles is the exact same size.
I went to the junkyard and got 2 wiring harnesses (that ran from the bottom of the A-pillar (disconnected at a large plug), and up to the front of the roof). I used 1 harness as my main one that ran alongside the original one in there, and the other one I used to extend all the wires to reach to the radio. I did this to keep everything in a factory-color-code scheme and to help with wiring. I left the original wiring harness in my truck because I have no 3rd door which means I have 4x10" speakers in the C-pillars of which no SUV ever had. If you have the 3rd door, you could probably get away with removing the original harness. I also got lucky and found a harness that had the exact options I had and was adding (lighted vanity mirrors, driver information center (or DIC), HomeLink). I learned that the Blazer/Jimmy/Bravada has a different stiffening bar in the roof that runs from B-pillar to B-pillar. The SUV's have a much wider and stronger one. This is where the clips were inserted into to hold up the back of the OHC. The S10/Sonoma has a narrow bar that runs from side to side. There is just barely enough room to mount the plate I made to support the back of the OHC.
Hopefully that covers everything.
To mount the front, it's pretty easy. All you have to do is grab a metal clip from a Blazer/Jimmy/Bravada (possibly the same one you got the OHC out of). It is located right above the rear-view mirror. That's it.
To mount the back, I used a 7"x14.25" plate riveted to the two brace bars in the roof. This kept the plate off the roof so that when the roof warms/cools, it can move freely. In the plate, two "riv-nuts" (or so I called them) were used in place of welding a couple nuts to the back of the plate.
After the mounting plate was done, I turned my attention to the headliner. In the junkyard, I cut a section from a Blazer that had the long OHC and used it as a template. I used a pencil to trace the openings and a utility knife to cut it. I cut from the side you see towards the backside to make sure it was a clean cut on the outside. Take your time. It cuts pretty easy.
So once the headliner was cut and done, the headliner was put back in. After the headliner, the OHC was put in followed by the sun visors, passenger grab handle, the garment hooks in the ext cab above the windows, and the original back dome light.
What the wires to the DIC connector do
7 = dark green - RAP Fused Supply
8 = black/white - Ground
9 = drk grn/wht - VSS
10= lt grn/blk - Outside air temp (this should be the only wire out of the cab to the sensor)
11= gray - Instrument panel lamp fuse supply
12= ppl/white - LED dimming signal
13 = NOT USED
14= Orange - constant 12v
15 = Yellow - Class 2 serial data
The connector for the DIC to the large A-pillar connector
7 (DK GRN) = P (DK GRN)
8 (BLK/WHT) = F (BLK/WHT)
9 (DK GRN/WHT) = N (DK GRN/WHT)
10 (LT GRN/BLK) = G (LT GRN/BLK)
11 (GRY) = E (GRY)
12 (PPL/WHT) = M (PPL/WHT)
13 = not used in the DIC connector
14 (ORN) = R (ORN)
15 (YEL) = C (YEL)
The large A-pillar connector to the Radio connector
P (DK GRN) = Radio PIN 9
F (BLK/WHT) = Radio PIN 5
N (DK GRN/WHT) = Radio PIN 16
G (LT GRN/BLK) = outside air temp sensor
E (GRY) = Radio PIN 7
M (PPL/WHT) = Radio PIN 6
13 = not used in the DIC connector
R (ORN) = Radio PIN 10
C (YEL) = to purple ALDL wire (OBD II port)