Aftermarket Keyless Entry Fuse Blows When Stereo Connected

I have a 1993 Ford Festiva L with 5-speed manual transmission. It was originally equipped with manual door locks and the factory AM/FM radio, and I added an aftermarket keyless entry system and power door lock actuators from Amazon. Everything has worked flawlessly for about 10 months until I recently installed an aftermarket AM/FM/MP3 stereo that I received for Christmas. I was able to use all of the factory stereo wiring without cutting any plugs or splicing wires, but since then the 15A fuse at the keyless entry module blows everytime I use the key fob, but only if the stereo wiring harness is plugged into the stereo. The factory constant power wire for the stereo is white with red stripe, which is also the color of the constant power wire that I have tapped into at the steering column for the keyless entry. It almost seems like the constant power for the stereo and keyless entry are being fed through the 15A fuse on the keyless entry module harness which is drawing more than 15A and causing the fuse to blow. The factory constant power wire for the stereo, although the same color as the other wire being used at the column, is a lighter gauge wire than the one at the column. I'm not sure what to try next, but I've gone through about 20 fuses so far trying to troubleshoot this. I was considering running a separate constant power wire directly from the battery to the keyless module to remove that load from the white/red stripe wire to see if that fixed it. Does anyone have any advice or suggestions regarding this that I could try? Thanks in advance for any help.

Does the aftermarket keyless entry have a parkibg light output? Does it flash the lights when locked or unlocked? The stereo should be drawing minimal power when you are using the remote fob, since the ignition switch is off. Disconnect any light flash output wires, or remove the fuse for them, if present. Then retest system.

Yes, the keyless entry module does flash the parking lights through a brown wire that is not fused separately. I will follow your advice and disconnect this wire and post my findings. Thanks for the help.

So I disconnected the brown parking lamp wire from the keyless entry module and it hasn't blown a fuse since! Even with the stereo connected and mounted in the dash the door locks continue to work properly without any problems. Thank you very much for your time and advice!

Do the parking lights work? Do your dash lights work? You connected the radio's ground wire to the illumination wire of the vehicle.

Yes the lights all work fine. I never had the radio ground connected to the illumination wire. All that I changed was that I disconnected the keyless entry module parking lamp flash wire from the car's parking lamp circuit. I am assuming that a problem has developed internally in the keyless module and it is drawing too much power to flash the lights now. With that wire disconnected and the load of the parking lights taken off of the circuit, everything is working fine. The stereo also works fine with no problems.

There is nothing wrong with your keyless entry module. Did you purchase a harness to install the radio? The illumination wire in the factory radio harness appears to be at ground, until you turn the lights on, then it has 12 volts on it.

I thought this problem was solved until this morning when I drove the car to work and it was still dark out. As soon as I turned the headlight switch to turn on the marker lights I heard a fuse blow. From that point on I had no marker lights or dash lights, only headlights, brakelights and turn signals. I checked the new stereo wiring diagram and there should be nothing from the aftermarket stereo wiring harness connected to the factory radio harness. I will have to pull the stereo out again and make sure that nothing is shorting the factory illumination wire to ground. I will post what I find once I'm done.

I will pull out the aftermarket stereo again and look, but there should be nothing connected to the factory illumination wire because this aftermarket stereo has no illumination wire. I didn't use an adapter harness for the installation because the factory dash harness was just standard size female spade connectors in a plastic plug, so I just plugged into them with insulated male spade terminals and made sure that they fit securely and couldn't short against anything. So at the moment, the keyless entry light flash is also disconnected which should mean no added load to the circuit. Perhaps there is damage to the wire somewhere along its run which is causing the fuse to blow when the lights are switched on? I will get in there and take a good look.

I pulled the aftermarket stereo and found that there was nothing connected to the factory illumination wire. I traced the wire back into the dash and found that it had been pulled tightly against the metal frame of the dash and had cut through the insulation on the wire. I repaired the wire, replaced the parking lights fuse and now everything works properly as it should.

I'm having a similar issue with my 2001 Toyota Tacoma. The fuse to the keyless entry module blew when I first tested the system. After disconnecting the parking lights (brown wires) and replacing the blown fuse, the keyless entry and everything else works great- except for the pyle aftermarket head unit. I'm worried I blew the unit itself. Another possibility is that I set up the keyless entry in accordance to the wrong trigger. I set it up for a negative trigger system, while it could be a positive. Might this cause a short in the system? The only difference between the + and - trigger setup is the placement of a yellow and a yellow/black wire (ground for a negative, constant 12v for positive). I grounded the wires where there was an existing ground wire, so my thinking is that this may be the ground for the stereo and I'm running a 12v current into it. It's either the setup, the head unit is blown, or some other issue unbenounced to me. No other fuses appear to be blown, unless the head unit has its own hidden fuse somewhere. The only directly applicable information I can seem to find anywhere on the internet is in this one forum thread. Please help!

Update: Problem solved! There's something called an on button- who woulda thought! Anyway, the head unit used to come on automatically when I started the car, but after installing the keyless entry, I have to turn it on manually every time. I thought it wasn't working altogether, but just wasn't used to seeing a black screen when I start the car. Plus, the on button is about the size of a pinhead! You live and you learn.

Maybe it's turning off every time because it shorts momentarily when I hit the unlock button each time to get in (due to wiring for incorrect trigger). Would that make sense? I'm just a high school kid working on his truck, so no expert opinions here.