Rebuilt radio causing ignition problems.

[FizzFury65]

I recently had the original radio in my '65 Fury III convertible rebuilt with FM, aux input, and Bluetooth capabilities. I replaced the old cracked speakers at the same time with new speakers designed for stereo sound. It sounds amazing, but the car won't start with it hooked up even when the radio is turned off. I'm not getting spark at the ignition coil, and I'm getting about 7.5V across the coil when trying to start it. When I unhook the wiring harness for the radio, it starts right up. Has anyone has this experience or any ideas on how I can address this?

 

[Big_John]

Something is wired wrong. Where are you picking up power and where is it grounded?

I'm thinking that the ignition is somehow being grounded out from the radio wiring.

 

[65Port]

New radio harness? Did you do the work?

 

[volksworld]

the only thing that makes sense to me would be if somehow the radio was getting power off the negative side of the coil...and the only way that might happen was if the car had a tachometer at one time and the wire from the negative side of the coil to the tach somehow got used as the radio's power source

 

[MrMoparCHP]

Another common mistake is assuming the two tires on the connector as +/- and not power and light.


Alan

 

[FizzFury65]

the only thing that makes sense to me would be if somehow the radio was getting power off the negative side of the coil...and the only way that might happen was if the car had a tachometer at one time and the wire from the negative side of the coil to the tach somehow got used as the radio's power source

This actually makes the sense. This was my dad's car, and he passed away when I was pretty young. Until a few years ago, it's been in my mom's garage without a lot of action. There has always been a cheap aftermarket tach attached to the steering column, but to my knowledge it's never been hooked up. There are wires from the tach just hanging below the dash, so there was more of an attempt made that I have no knowledge of. I'm not even sure if my dad would have done that or if it was done to the car before he got it in '90. I will have to do some real sorting through this rat's nest, but I should be able to find a place to splice it in that will make more sense.

 

[FizzFury65]

Something is wired wrong. Where are you picking up power and where is it grounded?

I'm thinking that the ignition is somehow being grounded out from the radio wiring.

It's wired back up exactly as it was taken apart, but clearly something is wrong. I'm going to investigate the tach theory shared below.

 

[FizzFury65]

New radio harness? Did you do the work?

I took it out and reinstalled it exactly as it was, but I did not do the radio rebuild. The tach theory shared below actually may make sense. Looks like I've got a pile of wire to sort through (it's a real rat's nest under that dash).

 

[mgm1986]

Definitely not a wiring expert but I do have lots of experience making mistakes doing wiring in my own cars.

The best advice I can give you is to disconnect the battery and start tracing with an OHM meter to try and make your own updated version of your cars wiring, focused on the dash to get your project sorted. This removes any potential of shorting something out, blowing fuses, dash lights or worse your fuel gauge.

When I had my radio rebuilt for my 1968 Fury III I recall the wiring harness coming back very different than what was originally on the radio. It was definitely not plug and play with the old harness.

If you go through the dash wiring and still have concerns, I would start tracing back through the firewall distribution block into the engine compartment to make sure the wires you think you are testing are indeed still wired as the factory intended.

Good luck with the project. Having a good stereo makes the car so much more enjoyable in my opinion.

 

[FizzFury65]

Definitely not a wiring expert but I do have lots of experience making mistakes doing wiring in my own cars.

The best advice I can give you is to disconnect the battery and start tracing with an OHM meter to try and make your own updated version of your cars wiring, focused on the dash to get your project sorted. This removes any potential of shorting something out, blowing fuses, dash lights or worse your fuel gauge.

When I had my radio rebuilt for my 1968 Fury III I recall the wiring harness coming back very different than what was originally on the radio. It was definitely not plug and play with the old harness.

If you go through the dash wiring and still have concerns, I would start tracing back through the firewall distribution block into the engine compartment to make sure the wires you think you are testing are indeed still wired as the factory intended.

Good luck with the project. Having a good stereo makes the car so much more enjoyable in my opinion.

Thanks. That's my plan. I'm going to start by cleaning out the stuff from the unused tach and trying to determine what may have been. I can then work my way back from the ignition coil to see where that was tied together, assuming that's the issue. While this is a mess of a wiring nest, I'm an electrician by day, so it isn't totally outside of my abilities. Thanks for the advice.

 

[Big_John]

The best place to tap in for the radio is at the fuse block.

Disconnect the battery. Unbolt it from the dash, turn it upside down and there should be a spade connection for the radio/acc on the backside of the radio fuse location. Depending if that is in use for something else, you may want to use one of these "piggyback" spade connectors.

The radio/ACC fused connection would be on the lower left side in this pic I found on the intrawebs. It has the cut off green wire connected to it.

 

[FizzFury65]

Thank you! That's ex eptiobally helpful. Hoping to be able to dig into that this weekend if I can't find time through the week.

 

[FizzFury65]

the only thing that makes sense to me would be if somehow the radio was getting power off the negative side of the coil...and the only way that might happen was if the car had a tachometer at one time and the wire from the negative side of the coil to the tach somehow got used as the radio's power source

This was 100% the issue. Everything is working perfectly now. Thanks for the idea! It was going to end up being fairly easily traced out as I went through it, but this gave me a pretty clear target, and I never would have understood why that wiring was even there. It was a good opportunity to clean up a lot of mess under the dash.

 

[mgm1986]

That is a great tip from @volksworld , glad you got it figured out and can enjoy your new stereo!

Curious, who did you have rebuild it for you? I used Tayman Electrical for my Fury stereo years ago.

 

[FizzFury65]

It really was!

I used R&B Vintage Radio (randbvintageradio.com), and Richard was exceptional. It's the original AM radio back in its place looking exactly like it always did, except now with a working radio lamp! He was also very attentive and interested in the process of this issue as well, which was great customer service I wouldn't necessarily expect.

I also swapped out the original 4x10 speaker in the dash and the 5x7 in the rear seat for new speakers from RetroSound. The old ones were the sort of cardboard junk you'd never know were bad with AM radio, but they were in bad shape. The new RetroSound speakers actually take a stereo signal and pack it into individual speakers. The 5x7 in the seat didn't fit particularly well and required some retrofitting of the brackets, but it turned out incredible in the end. I picked up my 6 year old from school yesterday, and he loved having music back there. His friends have all been fooled into thinking his dad is a cool dad, too, so there's an extra benefit.

That is a great tip from @volksworld , glad you got it figured out and can enjoy your new stereo!

Curious, who did you have rebuild it for you? I used Tayman Electrical for my Fury stereo years ago.

 

[mgm1986]

Cool, thank you! I will check them out when the time comes. I had good service with Tayman but their prices have gotten out of hand.

I used those same speakers in my '68 Fury and I did like them although I wasn't super impressed with their sound at higher volumes. When I get to the stereo in my '68 300 I am going to investigate other options including a small sub with two 4" speakers in the rear seat and front dash. Way ahead of myself though as I have some other more pressing safety issues to deal with. But going to the drive in with a working FM stereo is super excellent!

Enjoy being the cool dad, nice work getting the wiring resolved!

 

[FizzFury65]

The speakers, and music itself, is merely supplemental to the sound of being in a 383 convertible with glasspacks. That's where the real music is made. So I guess I can't say I will hear how great the speakers are in the end anyway.

I got the radio ordered a year and a half ago and only put it in recently, so I can't say what their prices are like now as they aren't listed on their site. I'm very happy with how it turned out though.