during initial startup we had some under dash electrical smoke due to ignition switch sticking.... so... before I button it up ( windshield/doors etc) I think I will just go ahead and replace the harness to be safe etc. YO has 30% off this weekend. Any inputs fit up etc? rally dash by the way...

I say it all the time, if your going to buy a new harness, take the time to compare/trace it out it to the factory service manual diagrams, compare it to the original harness, and take the time with a volt/ohm/continuity meter to check out the entire harness before installing it, the last guy I told to do this with his new M&H 70 RR/GTX harness didn't listen, and had to troubleshoot it AFTER it was in the car (lots of fun!)only to find a small break in a wire (undetectable to the eye, but not the meter)wouldn't let the ignition power up...

Mike

Thanks Mike. Will also replace the circuit board and test all gauges etc... is there ""how to" etc on testing gauges etc...?

To bench test gauges, I use a 6volt DC lantern battery (keep in mind gauges don't run on 12V)to initially check gauges for movement, if you have the sending units you can temporary wire up some of the gauges using the 6 volt battery for power to see how they register/ohm... the biggest headache is the fuel gauge and the sender/float for the B body

68-70 B bodies suffer from poor gauge panel/fascia/dashboard grounds (plus as restorers we compound this with heavier coats of paints, or paint where none was before), as well as the steering column, I always make addition ground straps to ground these to the body better

Mike

I used YO under dash harness on my 70 RR and had it install with no problems.It's been about 10 years now.All the wires were perfect length and color coded no cutting.The installer even told me I same a lot of labor by getting this harness instead of the painless one.I have no complaints.

The only one they sell for the 70 rr is actually for a 70 Charger. Be sure to find the green wires that go to the headlight relay under the dash and tape them up. They are hot. You don’t want them shorting to ground.

I agree, the M&H harnesses are great and I've had just a few minor issues over the decades with their products (nothing that wasn't easily solved/found), but it's always a good idea to double check anything and everything BEFORE install, as it's much easier to find any possible errors/loose connection/breaks/etc

Even NOS harnesses are to be suspect as well, I've had a few (just a handful) over the decades that either had wires assembled in the wrong terminals/junction plugs, or missing additional sections required to complete the harness...

Some like to assume it's "plug and play" with a new/nos harness, and that's just a dice roll that shouldn't be taken...