Hi All, I had an Aurora Design Digital Conversion radio installed in a original Ford Truck radio, back in 2019 and it worked great! Then I had the truck painted at a local body shop and all of a sudden it didn't work so great. AM & FM strangely all work good all the time with motor running or not, BUT... the USB and Bluetooth, they don't work when the engine is started and running. Once the engine is started the songs skip wildly from one to the next, and phone calls are disconnected. When the radio is just connected to the battery and the engine is off everything works great. So i returned the radio thinking it must have gotten wet, dusty or damaged while at the shop. I got the radio back now fully rebuilt all new components tested on a vibration table, even a new tuning coil, and its doing the same thing! Questions are..

1. What happened at the body shop to cause this? Or does it even matter at this point?

2. What will solve this problem? Noise filters, condensers? Which ones specifically and where to get them?? The folks who built the radio are at a complete loss. They said they've never seen anything like this in 40 years. So Im asking our 48-52 gurus here what has worked before?

The truck is completely stock. It has just been completely re-wired and is in great working condition. It is a 6v positive ground system. While at the body shop I painted the generator and I painted the engine.

Thanks and appreciate any help in answering these questions.

 

Sounds like ignition interference, and/or a bad ground. New paint means grounding areas covered with paint, poor contact. Try running a separate wire from the radio chassis directly to the ground terminal at the voltage regulator or at the battery.

Any chance you replaced the spark plug wires recently?

 

Battery power is very clean, voltage and current levels hold steady as the battery discharges. Problems usually do not arise until the battery discharges below a certain voltage. That said, within an automotive electrical system, the battery is there primarily to provide power to start the engine. Once the engine is running the source of power is the generator. I agree with Ross, there is something that has been introduced into your electrical system that is causing interference in your radio. I would start at the generator and work your way to the radio...somewhere there is a ground missing or a poor connection. An improper ground can act as a capacitor and make a simple DC circuit oscillate...in simple terms, noise is generated and it is jamming the radio.

 

hi Ross, yea we changed the spark plug wires coil, new battery, but that was about a month after I got it back from the body shop. I had the problem with the radio immediately after it came back from the body work. All grounds we’ve used are clean but I’ll check again for sure. What’s strange is the Am & Fm module in this thing works fine with the engine running and is unaffected , but it’s only the portion of the radio that controls the usb and Bluetooth that goes crazy..?

 

Ross and Charlie have some great suggestions. It indeed sounds like something has changed with the truck being painted. It indeed sounds like
grounding integrity has probably changed with the fresh paint job. You mentinoed you painted the generator. Between that and a freshly painted firewall you may have a bad or loose ground(s) at either the generator or voltage regulator or both
So I would check to make sure the voltage regulator mounting base and the ground wire connected to it are making good , tight ,clean , sheet metal connections, and the same on the generator side. If one of those connections are loose especially at your voltage regulator a lot of noise could be created in your charging system and that could be scrambing the digital processor in the radio handling the USB and Bluetooth modes. Is the cab sheet metal grounded to the engine block and the engine block grounded to your frame? If all that appears good something else to try is to temporarily wire your radio directly to your battery. Both the radio hot and ground wires. If that works now with your engine running I would go back through your charging and grounds system like mentioned earlier. I am thinking that during the painting process things such as your voltage regulator, radio antenna, radio itself, and any ground wires to your firewall may have been removed, but after painting now needs some good bare sheet metal to reestablish a good ground again.

 

I'll throw this out there to see if it helps :: I had upgraded the radio on my 2005 Ford Expedition to a touch screen digital radio, and when the voltage dropped below an acceptable lever, all sorts of things you are describing would happen. I replaced my alternator, as the running voltage was not suffiicient for the new technology, plus it was actually going bad. Check your running voltage at the battery, if it's not over 14V, you're going to probably have issues with digital technology.

 

Or if he is still 6 volt.... then over 7 volts?

 

We're getting a little over 7 volts at the radio. All the grounds are good, the truck has just been totally rewired and all new grounds were established. All basic diagnostics were done like grounds, voltage etc. But obviously more stuff has to been done to isolate this problem. I agree its gotta be something coming from the engine but what doesn't make sense is why only the USB and Bluetooth are being affected when they're being powered through the FMR module?.\ And why was it working before and not now. Very strange. I somehow think this has something to do with the generator (painted) or antenna (changed and moved to a OEM location) since those were things that were altered in at the body shop. Its been said that installing a set of the original type of noise condensers would help but they're almost impossible to find?

 

Are the new spark plug wires radio-suppression type, usually carbon-core? Those usually take care of ignition interference.

I don't think there's anything real special about radio noise condensers. The shop that converted the radio should be able to supply some, or at least point you to some.

I'm not sure but I believe the antenna mounting has to be well-grounded, to ground the shielded antenna cable.

 

Funny you mention this Ross, I spoke with a really nice older gentleman today who is another dealer in these radio boards who has about 50 years of experience in car radios, and he said the same thing about spark plug wires and to ask if they are radio suppression type. Ive never heard of this. I replaced the spark plug wires with a type of reproduction spark plug wire that is the OEM type for a 52 Ford truck. Im not sure it would be of this type or no? I could find out. I replaced the wires about a month after being back from the body shop. As far as I remember this problem arose immediately after coming out of the body shop and the problem has stayed with me even after re-wiring the entire truck and having the radio rebuilt again with all new components and then having the tuning coil replaced. So the radio has been back twice for the same problem. It's probably the truck at this point but still not convinced of it and where its coming from we have no clues yet. Right now we are going to replace the Regulator and then run some tests suggested by the engineer at Aurora and some of the tests suggested here.

I wish the shop I bought the radio from would be able to post me or supply me some condensers! Apparently they are not obtainable any longer?

 

A condenser is simply a capacitor...while the old wax filled OEM condensers may be unobtanium today, but modern capacitors with the same electrical properties are readily available. I don't have the data at my fingertips but with a little research I am sure you can find the capacitance value of the OEM condenser and go from there. In this application the capacitor shunts high frequencies found on the DC voltage line to ground much the same way as the high tech car stereo guys use giant capacitors to stabilize the voltage inputs to their amps. Manufacturers are still making the device that you need, you just need to identify it in electrical terms instead of a FOMOCO part number. Good luck...

 

Thanks Charlie!! I will look into this.

 

Ross has pointed out somethings that are really interesting. The spark plug wires and the antenna ground. I will just talk about the antenna. You mentioned you had moved the antenna to the stock location. Maybe there is some fresh paint keeping the antenna cable and mount from grounding correctly. A quick test might be to unplug the antenna cable from the radio and with the truck running see if your Bluetooth/USB is now working correctly. If you have a bad antenna ground interference could come in through the antenna and antenna cable. You would think it would also be problematic on AM, (you mentioned earler that you thought AM and FM worked normally). Its just a quick test and would eliminate another possibility. Also earler I mentioned you might try to temporarily connect your radio's power leads right to your battery terminals and then run your engine and try your radio's functions. You get a chance to try that?

 

Great suggestions hooler! Yes we will try those tests. Right now truck is waiting on a new regulator just in case easy swap as some tapping on cold starts was heard. Truck is at an electrical shop where we’re finishing up a bunch of accessories and a full rewire. But it’s a stubborn problem that so far is evading common corrections. I appreciate the direction!

 

Thank you 52flthed! Hopefully it helps. Let us know what you find out!