Radio Fitting Hassles

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Joined: Fri Aug 14, 2020 11:14 am

Radio Fitting Hassles

Post by YPE832 » Fri Aug 14, 2020 11:24 am


I'm fitting a new Kenwood into my 78 Roadster and I'm have painful time with power and the head unit.

I inherited an ignition live off the green / white wire on the loom. I put my own earth into one one of the screws that holds the glove box in place - both are good (tested earth off the ignition switch itself and the ignition live. I took a feed off the purple wire running into the clock for my perm live (clock still happily ticking along).

I've got no fuses blown in the car, or in the head unit itself.

I wired one speaker into the speaker iso block, powered it on a it ran fine. I powered off, disconnected it all and went to fit the speakers into the doors, route through the car etc.

I then went to connect it back up and - dead as the proverable. So I unplugged the new speaker, reconnected and still dead. All fuses checked and fine.

Stripped back all the tape I'd put around the connectors - all showing just over 12v in ignition or perm live on car side, when reconnected showing same on radio side. Checked my ISO block both sides and over 12v.

The supplier for the head unit kindly put it onto their test ISO block for power and it came straight up, so I know I've not popped the head unit somehow.

Gave it one more go, still nothing.

I took the main plug out the radio (has its own consolidation connector from the ISO block). Checked there - 10.8v. Perm and Ignition.

Thinking this is odd - I go back to the car side of the ISO connectors - 10.8v.

When I start the car, the ignition light stays on until lifted off tickover - so I'm thinking, have I made a bonehead wiring decision or have I got a starter / alternator problem ?

Any advice / help greatly welcomed !

78 MGB Vermillion Roadster, fast road engine
72 E-Type 2+2, fast enough stock

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Joined: Sun Jul 26, 2020 2:47 pm
Location: Sunny South East

Re: Radio Fitting Hassles

Post by Senninha » Fri Apr 23, 2021 3:14 pm

Just a thought (from a non electrician), but reading back you say the problems started after you’d run the speaker install ... so my logic is to ask have you by chance managed to trap a speaker wire that is creating some kind of earth / short that is stopping you enjoying the install??

HTH, Paul
'Too many manufacturers today are obsessed with lap times and power outputs at the expense of emotion and fun' Colin Goodwin

Saving (and learning) for an MGB GT
AMG C43 - Daily driver
NSX - 1 of 1 - 3.2 Targa

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