Radio Clicks when shifting

[Bill L.]

What could cause the radio to click when shifting gears.

It is an original AM/FM Stereo Radio and the trans is M20.

The only electrical part on the trans is the back up switch. The back up lights work fine.

Thanks,



Bill

[Terry M.]

Re: Radio Clicks when shifting

Something (an electrical connection) loose in the radio, or something contacting one of the speakers or speaker terminals.

[Alan S.]

Re: Radio Clicks when shifting

Hi Bill,
Could the TCS switch on the transmission be causing the click?
Regards,
Alan

[Terry M.]

Re: Radio Clicks when shifting

Hi Bill,
Could the TCS switch on the transmission be causing the click?
Regards,
Alan

Bill hasn't told us which gears cause the noise, and hasn't even told us the year of his Corvette (Yes it makes a difference for the TCS) except his profile says he owns a 1970. 1970 TCS solenoid operates in third and fourth gears if the transmission is the original and all parts function. 1971 and 1972 will operate only on entering fourth gear.

[Jack H.]

Re: Radio Clicks when shifting

I'll take a WAG...

The reason the factory put a ground strap on the exhaust pipes to the frame's center cross member, was to defeat potential radio RF. Exhaust is highly ionized as a fluid and much of the piping from the exhaust manifold back is insulated (hanging in the air, suspended from the frame by non-conductive rubber straps).

The ground straps at the center cross member give static charge developed by exhaust flowing through the pipes a discharge path to ground vs. allowing that static to build and then randomly jump the air gap between the pipe(s) and the chassis. Could this car be missing its exhaust ground straps?

[Michael H.]

Re: Radio Clicks when shifting

At some time in the early 70's, GM sent a TSB (technical service bulletin) to dealers about this issue. I don't remember the exact year or the recommended repair though.

[Patrick H.]

Re: Radio Clicks when shifting

At some time in the early 70's, GM sent a TSB (technical service bulletin) to dealers about this issue. I don't remember the exact year or the recommended repair though.

Turn off radio.

[Mike E.]

Re: Radio Clicks when shifting

Don't shift.

[John H.]

Re: Radio Clicks when shifting

Did that year car have a clutch safety switch? That would cause a "make-break" situation every time the clutch pedal was depressed, although that purple wire circuit only has power with the key in the "start" position. Camaros had that switch from '69-up.

[Terry M.]

Re: Radio Clicks when shifting

John,

That is a good suggestion. His 1970 does have the clutch interlock. I remember seeing a bright blue "Scotch Lock" connector to a capacitor right above the pedals on my 1970. It might be for the brake lights or the clutch interlock, I don't know which, but a look at the U69 section of the AIM might be revealing.

[Richard M.]

Re: Radio Clicks when shifting

lol.....You 2 guys have some great ideas.......

Could it be the neutral start safety switch? I've seen it on some C3 schematics so I assume it's activated with the clutch pedal. I would also assume that when you shift a M20 you depress the clutch.

Did C3's use a radio condenser on it?

Rich
p.s. see....I don't just do C1's & C2's

edit- ah-ha....just as i was writing this I see John got it be before me.

[Paul O.]

Re: Radio Clicks when shifting

Bill hasn't told us which gears cause the noise, and hasn't even told us the year of his Corvette (Yes it makes a difference for the TCS) except his profile says he owns a 1970. 1970 TCS solenoid operates in third and fourth gears if the transmission is the original and all parts function. 1971 and 1972 will operate only on entering fourth gear.

Terry

1971 had the CEC system and operated in 3rd and 4th gear like the 1970 1972 system only operated in 4th.

Paul

[Bill L.]

Re: Radio Clicks when shifting

Great ideas. Mine is a 70 L46 with M20. Everything is stock. AM/FM Stereo recently redone my Jerry and sounds great otherwise.

It does happen regardless of whether it is running or not. However, it does not occur if the radio is on and the ignition key is turned to the accessory position.

It only occurs going in to 3rd and 4th gears. I am thinking Terry may be on to something regarding the TCS.

I am guessing that just unplugging it at the Transmission might isolate the problem. I know the TCS solenoid by the carb no longer functions.

Keep the ideas coming! I think we are getting close.

I also have an alternator whine but I am guessing my 40 year old capacitor on the coil is the culprit there. It is the original alternator and it has been redone correctly by an NCRS member.


Bill

[Patrick H.]

Re: Radio Clicks when shifting

I know the TCS solenoid by the carb no longer functions.

Bill

Often repairable, else they do make a new replacement.

Patrick

[Terry M.]

Re: Radio Clicks when shifting

Terry

1971 had the CEC system and operated in 3rd and 4th gear like the 1970 1972 system only operated in 4th.

Paul

Since you had a 1971, and I didn't I will bow to you, but I always thought other wise as far as which gear(s) gave vacuum to the distributor. And as far as the transmission operating the solenoid -- it doesn't matter what the system is called. Those engineers made a job for themselves changing those systems each and every year, and for what? Not much functional change for a lot of different parts -- and at that GM made a ton of money in those years. Go figure.