Radio seems to disconnect from the battery... sometimes

[rgk]

Hi. Just hooked up a new radio, but when I go to start my car, the station has not been saved, nor has the clock. In fact, the entire thing resets. I thought perhaps I hooked up the battery cable incorrectly, but I checked this and noticed that the radio DOES save the station, time, etc., for a while. However, if the car is left off for a longer period of time (not sure how long, have not experimented with this enough yet), it resets.

My clock used to stop working intermittently. It would start working again whenever it wanted to. Some time ago it stopped working completely. I suspect these two things are related. No other electrical issues, though the rear lights are a disaster. Any ideas?

Thanks.

[billofdurham]

Is this a Volvo or after-market radio?

Bill.

[PaulSimonon]

Sounds like your constant wire to the radio isn't working, or you hooked up the signal wire to the constant power, or both.

The clock and the constant wire on the radio harness are indeed connected, and if one isn't working the other won't either. Check the wire and check clean the connections.

I don't know what car you're in, but on a stock 240, the wire is solid green and in most aftermarket harnesses I believe yellow with red? On a 240, it runs from fuse 8. If you need more information, let me know and I can try to help you out as best I can.

[rgk]

This is a Mitsubishi am/fm cassette stereo purchased on ebay. It was apparently taken from a Mitsubishi vehicle.

The only wire with any voltage is a black/yellow wire. I hooked this up to the stereo's yellow "battery" wire. The only other wire that is not a speaker wire, aside from the ground, is green. I hooked this up to the stereo's red "constant" wire. I noticed that when I connect the car's black/yellow and the car's green, the interior lights come on. They stopped working some time ago, but I can't say with any certainty that this occurred after I cut the wires from the old radio.

In order to have both a working stereo and interior lights I connected all four wires - yellow/black and yellow constants, and red and green battery wires - together as one. But like this the stereo still resets after a few minutes of shutting the car off.

PaulSimonon, I'll take your advice and check that wire's connection.

[rgk]

OK, problem solved.

The main problem was a blown fuse. It probably blew when I was first attempting to install the radio months ago without knowledge of how the stereo grounds (more on this later).

After replacing the fuse I noticed that the stereo remained constantly lit, and constantly displaying the time. Although this was an improvement, I didn't think it was quite right, so I pulled out the stereo and disconnected the four-way ignition-battery-ignition-battery connection mentioned in the post above.

At that point I noticed the interior light was still on, so the fuse must have been the culprit there. I wasn't entirely sure which wire should go to which, as I knew the car's green wire was the battery wire, but the wire coming out of the new(er) stereo harness had "battery/ignition" printed on the yellow wire. I have schematics for the car wiring, which mentions separate "battery" and "ignition" wires. I matched up black/yellow to yellow, and red to green. The stereo remained lit, even if the key came out of the ignition. This being an '85, I thought this to be improper. I know old cars' radios shut off after taking the key out of the ignition. I then remembered that the schematics for the radio harness mentioned that the yellow wire was "battery" and the red wire was "constant." I matched up black/yellow with red and separately matched yellow with green.

Bingo. The stereo worked upon inserting and turning the key, turned off upon removal, and when turned on, it retained the clock/tuning settings. "Constant," it seems, serves the same purpose these days as did "ignition" back in the early '90s, when my car's schematics were printed. Of course, it didn't help that my car's schematics were 84 and prior, and that I had an 85. The Hayne's Volvo Repair Manual I own is a godsend, but it simply does not have the radio schematics for 85 and later. It mentioned nothing of a black/yellow wire. Some of the colors were right, while others were not, and their function had to be deduced through reasoning.

The car's clock, however, still does not work.

I had trouble installing this stereo for the longest time. It seemed as if there was no power coming in to it, even though my old stereo received power. I took the stereo itself to a large electronics store that offers car stereo installation and asked the employee there if he could test it. It worked, which was a relief, as I was beginning to doubt the ebay seller from whom I had made the purchase. The employee opined that a bad ground might be the cause of the problem.

Long story short, it turned out that I had to take my black ground wire (the one that is thicker than all the rest of the stereo wiring) and attach it DIRECTLY to the STEREO'S chassis. I did this using a special (yet inexpensive) green grounding wire. The green grounding wire has exposed wires, which I connected to my car's black ground wire using a plastic electrician's connector, on one end, and a metal horseshoe which I slipped underneath a bolt, on the other. I screwed this bolt directly into the exterior body (shell, chassis) of the stereo. I never knew stereo power operated this way, but received another hint from a printout I found online which contained the schematics for the harness which I purchased specifically for this Mitsubishi stereo. It said something like NOTE: some of these stereos require direct ground connection to the chassis. Although the hint wasn't specifically clear, I received a flash of intuition when looking at the stereo, experimented, and succeeded.

Thanks, all.

[billofdurham]

Good job. Thank you for the update.

Bill.