Conversion to electric speedometer/wiring 4wd indicator light

Discussion in 'The Garage' started by dyeager535, Apr 27, 2005.

  1. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
    Likes Received:
    Roy WA
    I figure some probably laugh at a 4WD indicator light, but hey, the '91 205 has the switch for it, why not?

    Finally got the time to start wiring both of these up. Thought I would post up what I've found/experienced so far for anyone that might consider it, such as going to a '90-91 241 or 205, and keeping the stock gauge cluster.

    First thing first, which might be of use to more than the below info...the cluster light "holders" (the plastic piece the bulb plugs into) changed somewhere around '90-91. My earlier cluster uses a bigger holder. Luckily I had the holders from the '81-88 RWD Olds Cutlass' handy, and they are the same smaller size. Weird change.

    The 4wd indicator light wiring is "interesting". Very easy to wire, but the connector at the t-case isn't. I'm guessing this is a 205 only issue, but the switch is so close to the body that I couldn't get the connector on it. It's weatherpack, I just went to the wrecking yard and found a 2 prong weatherpack to use. Weatherpacks are "keyed" so you need a matched set. Of course the one I got didn't match. No problem, just cut a "key" in the connector yourself with a razor knife. Also trimmed the plastic "towers" of the weatherpack down so I could get the connector to fit between the body.

    The later 4wd lights (241 or 205) are obviously simpler than say, the 1980 205 indicator light setup my friend pulled for me. Older ones actually have the wiring running to the gauge cluster bulb socket. On the '90-91, when the switch closes, you just need 12V to the instrument panel connector pin that corresponds to the 4wd light bulb. Basically, get 12V ignition switched from the fuse panel, run it to the 4wd switch, then run the connector from the other wire up to the cluster connector, and solder a pin for the cluster connector to that wire, and plug it into the right spot. Easy. Wire routing is the hardest part.

    I used the split plastic wire loom, took one of the seat belt bolts out closest to the t-case on the drivers side, put in a longer bolt, bolted the seat back down, then used a clamp held in place with a nut under it to keep the wiring tight against the body. Also will keep it away from the driveshaft. Run it up the frame into the engine bay with the VSS wires from the t-case, through the grommet that the speedometer cable used.

    As to the electric speedo cluster. The cluster connector of course did not change. However, the connector wiring is ENTIRELY different than the 1986 cluster I'm replacing. Only one additional wire in my case (for the speedometer input from the DRAC) but the pins are almost all in different locations than earlier.

    Didn't feel like using the manual for the clusters, so I de-pinned the connector in the truck, and re-wired it according to the back of the '90-91 cluster. Plugged it in, turned the signal on, brake light blinks, both turn signal lights flash, knew there was a ground issue, then nothing. Popped the gauge fuse. :) Checked everything again, and a ground isn't just a ground with that wiring. Found an actual dedicated ground (about 9 of the 18 wires at the connector are grounded with nothing on, doesn't mean all dedicated grounds) then started plugging in the turn signal light pins, etc., one at a time. That worked.

    Not quite finished yet, a few more pins to go, only get to work on it one day a week if that. Still have to mount and wire in the DRAC, luckily some of the stock dash holes near the ashtray are spaced for DRAC mounting.

    I might post up the pinout for the '86 and '90-91 cluster when I'm done, although it could just be scanned from a service manual.

    No idea why I typed this, I guess someone might get something out of this. Would kind of be a waste if I didn't post what's caused problems or worked when doing it just in case someone else needs the info in the future.
    Last edited: May 2, 2005

Share This Page