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2003 Dodge Ram 1500 4x4 130k miles 5.7L engine. lovely old aftermarket CD player. Big amp and subwoofer. I replaced my truck battery 1-2 weeks ago. It has sat in the driveway since. Today, I started it and eventually my wife drove it around for a couple hours. It was rain/snowing all day long. She commented that when they got back into the truck, the radio was already playing before ever putting the key in the ignition (this never happened before). I checked the battery leads and ground for the amp. Everything was fine. I disconnected power to the amp and the CD player was still powered on. I removed the CD player from the dash and all the connections in the back of it looked normal. I disconnected the battery, let it sit a minute, reconnected everything and the radio was instantly powered on (no key in ignition). The only thing that changed today was that the truck was driven during the rain/snow. Maybe rain/snow got into the door while it was open and the window/lock controls got incidentally wet. Could this be related? No idea. I tried searching the internet but couldn't figure out what terms to search and got lousy results. I tried toggling the ignition on/off many times to no avail. I pulled codes and the only code is P0138 for an O2 sensor. Lastly, when the key was out, radio on, if I pushed the cigarette lighter IN, the radio would power off. As soon as I released the cigarette lighter, the radio powered back on (no key). What could be causing this? I disconnected the battery and left it that way until I can figure it out. Any help would be greatly appreciated.
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Dec 28, 2018 02:58
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| # ? Apr 19, 2024 12:23 |
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If you hold the cigarette lighter in, and turn the key on, does the radio come on correctly? And if you leave the lighter pushed in until it heats up, does the radio eventually come on while it's in, or not until it pops out? It sounds like some poo poo's getting shorted together and sending power to the ignition pin on the radio, which is what triggers it to turn on. A multimeter would be very useful here if you don't have one already.
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Dec 28, 2018 03:13
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I'll try that more tomorrow. I do have a multimeter but I wouldn't know what to check. If you have some (very specific!) suggestions I'd be super grateful.
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Dec 28, 2018 03:17
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The main thing I'd think of right now is to check for continuity between the "ignition" or "switched" pin of the radio harness, and the hot pin of the lighter port (usually the center pin down at the back, you can double check with the voltage function to confirm). For the radio you should be able to find a connector pin diagram for either the radio itself, or if the PO was slightly dumber and hardwired it, for the original Ram plug for the factory radio. You want switched 12V, not "constant hot" or "B+". If everything's correct you should read no continuity between the lighter and the switched pin; if you get anything else, even a somewhat high resistance value, you've got a short somewhere.
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Dec 28, 2018 03:26
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Interesting. I have a similar issue with my lovely Durango. Went out to fire it up and the battery was dead. I pulled the battery out and threw it in the charger where it took a normal (if deep) charge. Threw it back in, let it sit a week and it was dead again. I finally realized that the (broken!) radio was staying on regardless of the key position. I only drive the thing once a week so I can’t be bothered to troubleshoot it... i pull the + cable and reconnect it when I need it. Lol mine throws the same P0138 code. I have the O2 sensor on hand somewhere, but again i only drive it once a week so who cares? next time i do an oil change i’ll deal with it it
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Dec 31, 2018 18:27
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