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I am attempting to re-install a new Left hand dash panel back in the car. The wiring bundle seems to bind up and get in the way so the panel will not sit back where it can be attached. Where should the wiring harness be routed? The AIM shows it below the speedo/tach cables but that seems to cause problems. The gauges had wire retainers at the upper left and right as if it went above everything. Apparently the problem is I am not the first person to have ventured back here.
I just checked my 69 AIM and under UPC 12, sheet B11 it shows the harness low and running behind the speedometer and tach just like my 68. The retainers are mounted low as well. It took a little work, but I was able to get it in place with a new harness that wasn’t exactly flexible. Keep at it, you’ll get it.
On my 72, the bundle goes up over the speedo and tach. I am reasonably sure no one has monkeyed with this on my car.... It's just really tight there. Excuse the mess, haven't dusted yet....
When you are sure of how the bundle fits place it on a baker "cookie sheet" in the sun for a couple hours to make it flexible so that you can "stuff" it into those tight spots.
Last edited by doorgunner; 06-17-2018 at 08:26 PM.
GM changed the routing of the dash wiring harness where the speed/tach are concerned.
On a 1969...like previously mentioned ...it is routed LOW on the gauges and NOT up high like on a 1972. GM changed it in 1970 and routed the wiring harness as like what you see in POST #4.
I can say I HATE working on the 1968 and 1969's in this area due to how this harness has to fit.
I often times will use my heat gun to slightly heat up the harness to soften it and make it a but more pliable.
Thanks to all for the advice and tips, probably the single most infuriating frustrating thing I have done with an automobile in the past 40 years though no need for a heat gun down here in lower Alabama these days.
YES...installing this wiring harness will test the conviction of anyone who tries to put it in. I am SO GLAD GM routed it differently in later years. There is NO comparison between them in the area around the speedo/tach area..
Hi guys... These are great pics however they show the back of the tach/speedo assembly with the dash removed. Is it possible to put the dash in with the assembly in place? I have no idea how that is possible. I am in the process of reassembling my 69 dash with a new dash harness and there just doesn't seem to be much room. Don't want to damage anything. Thanks!
Last edited by 5869Corvette; 04-03-2020 at 08:09 PM.
Reason: more info to give
In my case, all that assembly is together; anything that goes to that lower dashpad on the driver's side is there all hooked up. I didn't have any trouble installing the upper dashpad, no interference with the bundles there. Hope that helps
Nightmare. I have had the lower dash in and out a few times. The first was to rebuild it all and add back all the parts Bubba left off, fix broken gauge light wires, replace the headlight switch and vac lines. Putting it back in, the speedo stub for some reason lines up exactly with the upper curved dash brace (roadster) not allowing me to slide the speedo cable on. Back out. Put the cable on first. Try to put back in. Now the pad flexes to where you can’t get the lower screw on the left side in. Back out. Move harness a bit. Back in. Blue striped hose comes off at headlight switch. Back out. Break another old gauge bulb wire. Fix that. Back in. Jam trip odometer cable against wire harness. Back out. Fix that cable. Back in. Now, the pad doesn’t fit around the steering column properly on the left side and the tabs for the lower close out panel are nearly coming off. Oh, and taking the steering column out meant losing the old steering column seal. Have a new one. Also bought a new lower pad. Will rebuild it all again when it shows up.
When I did my work there, I was replacing all the bulbs with LEDs, so my task was only to move that lower dash back (rear-ward) enough to get my hands in there. I only dropped the steering wheel and unhooked the speedo and maybe the tach cable. Through this process I did not pay enough attention to the stupid odometer cable, so it doesn't work unless I use a pliers on it.
When I went to LED strip lighting on my 1968 I extended some of the leads of the harness for those lamps (and it's really only one lamp power connection now). I had previously extended most of the rest of the harness and had soldered in some disconnect connectors. I have 2 connectors one for the tach side and one for the speedo side such that I can disconnect the harness before removing the dash.
This final extending allowed me to relocate the main bulk harness to "above" the speedo & tach. I also had removed my steering column this last time (should been doing it all along - it's so easy) so it was easier to adjust and reinstall everything.
Sammy T... painful but hilarious. Bubba strikes again! Gotta keep that humour as you work through it. Kansas, the trip odometer cable has to be disconnected from the hole in the fixture at the bottom of the lower dash pad then wound around the harness and inserted into the hole. Hellish but it’s the only way. Also, the odometer and tach cable have to be disconnected on the engine side of the firewall which gives you the ability to pull them forward to connect them.
I was able to reorient the 2 sets of wires and bulbs that go on either side of the steering column (trying very hard to not remove it) and line them up so that when I drop the lower dash in that I’m not pulling on things. Did this by warming it up with the heat gun (still chilly here in Canada!) I am still trying to figure out how to accomplish installing the upper dash pad with the lower one already in. Attached a pic with harness wires correctly oriented.
When I went to LED strip lighting on my 1968 I extended some of the leads of the harness for those lamps (and it's really only one lamp power connection now). I had previously extended most of the rest of the harness and had soldered in some disconnect connectors. I have 2 connectors one for the tach side and one for the speedo side such that I can disconnect the harness before removing the dash.
This final extending allowed me to relocate the main bulk harness to "above" the speedo & tach. I also had removed my steering column this last time (should been doing it all along - it's so easy) so it was easier to adjust and reinstall everything.
I have been giving the idea of six pin connector for the speedo side and an 8 pin connector for the tach side just to make it all easier. I like it and nobody will see it...unless they take the dash out.
It’s a great thought. I just hate the idea of taking a new harness and doing that. Sure would be nice if Lectric or one of the harness guys would offer a version like that.
I tell ya.... it's well worth it. I've learned something every time I've taken my dash out. Just make sure you solder and heat shrink the connections to avoid future problems--and extend them as you see fit.
There's a bunch of lessons out there and I'm pretty good about learning them, but sometimes I'm a maroon.....like that lesson to just remove the steering column. Egad!! I should have been doing that from the start--- it makes everything so much easier.... and it's so easy too.
Originally Posted by Sammy T
I have been giving the idea of six pin connector for the speedo side and an 8 pin connector for the tach side just to make it all easier. I like it and nobody will see it...unless they take the dash out.
agree with carriljc..
extend and minimize the connections... such as all the light wires...
so much easier.
i extend them about 1 foot....that way I can install all of the wires/connectors before I slide the instrument clusters back in place
My Opinion: There is nothing on a C3 more difficult to work with than the interior!
I was struggling getting the 68 speedo/tach dash panel reinstalled due to interference with the wire harnesses. Finally I took the dash panel aside and removed the speedo and tach cannisters and installed the dash panel sans these two components. Looking inside, through the speedo/tach holes, I imagined the space the cannisters would occupy and moved the wire harnesses around to make room. Also remember to consider the tach and speedo cables.
I used the same technique to install the 70 speedo/tach panel last week.
One thing I do to make replacing the center gauge bezel and speedo/dash panel is to alter the main under dash wire harness. I cut all the wires from the harness going to the dash panel and bezel. I then lengthen each wire run and install an interim connector. After I install the dash panel and bezel, I have wires and added connectors hanging down and I just snap my added connectors together and push them back behind the dash panel to hid them.
For example,,,,look at all the grey wires coming from the under dash harness to the speedo/tach lights. I cut these wires in two. The grey wires coming from the harness are made longer with butt connectors and added grey wire and a connector half is installed. The light bulb assemblies are snapped into the speedo and tach and once again their grey wires are lengthened with butt connectors and added grey wire and another connector. When I instll the speedo/tach dash panels, these connectors are hanging down. Snapping them together connects the lights to the dash harness....no laying on my back trying to push the lights into the speedo/tach cannisters.
My latest problem: the tach cable interferes with the bracket used to mate the steering wheel column to the windshield frame. I'm planning on buying an electric tach. Might as well. This will avoid buying a HEI distributor customized for a tach cable drive.
06-16-2018, 04:28 PM
1969 dash wiring harness routing
