20 Most Recent JBL MR-4 AM / FM / CD 180 Watts Marine Receiver - Page 5 Questions & Answers

unfortunately that's going to be a labor intensive project. You will have to follow the wires to where they go and make sure that they are all tight.

Being that the sub stays on you know you are looking for a loose wire off the other amplifier or the head unit depending on how you are powering those speakers.

if you have two amps one for the subs and one for the mains its probably not the power or ground going to them since both are not shutting down but check where the power splits to each amp.


start at the amp that isn't working unhook the cables. Test that those cables have power and proper ground then make sure they go back on cleanly (no loose strands) and tightly. proceed to follow the power wires to where they are connected.and double check everything.

If you have access to a continuity and voltage tester that will make it a bit simpler.

Depending on how clean an install it is (no panels, speaker boxes amps or seats to remove) it shouldn't take more than an hour or so. I always recommend that connections to power blocks remain easily accessible as I have had to remove amps, subs and junk like neon to get at wiring and its always a nightmare.

hope that helps

You really should try to get to the amp. There might be a fuse blown. The glove box is fitted with a few screws which are hard to locate, but they're really there!

Run a jumper between the power wire and the remote (disconnect the remote wire from the head unit first). If the amp turns on, you got a blown fuse, or other problem with the remote turn on from the head unit.

You want to pick up a wiring harness for your truck at your local parts store or online, should be petty cheap. Then all you have to do is match up colors, ie purple with white stripe to purple with white stripe. The other thing you can do is hook a9 volt battery between the similar colored wire pairs from your trucks wiring. Then you will know which pairs go to which speaker. The other ones you need to know about are red, black and yellow, they should correspond directly to your trucks wires, red and black are power and yellow is the accessory

Hi Adrian,
To be honest, it depends on your amp, also on whether this is a dual voice coil sub or a single.

As a rule, if the sub has a dual voice coil (2 sets of connections) then connect the 2 positives together and the 2 negatives and run the 2 sets of cables to one output on the amp.

Check your amp specs to make sure that it will run @ 2 Ohms as this is what will result.

If your amp isn't 2 Ohms stable then you will have to wire each voice coil to a separate output on the amp.

As you said "the left rear speaker blew and became very hot". This is a symptom for problems at the amplifier stage (burn out internal amp parts, not protected by any fuse and giving DC output power at the speaker may cause this exact kind of problems at the speaker). I suggest a full check for the JBL amplifier at a service center. I don't suggest to use this amp at another speaker. This may destroy this speaker also. Depending on the exact kind of problem at the amplifier you may have to check the wiring between the amp and the burned speaker also, before you install the amp back to the original location.

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the outputs can be getting weak in the circuitry or a corroded ground to the antenna

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