2014 Dodge Ram RF problem

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niagara16
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2014 Dodge Ram RF problem

Post by niagara16 »

We have installed several motorola PM1200 radios into 2014 2500/5500 Dodge Rams. The problem is no matter where place the antenna RF seems to get into the dash board, Trailer brake system and computer. Before pushing this off to dodge and a shield problem of there cables i am looking for ideas to try. I have tryed mag mnts that go all the way back to the rear bumper. I have only solved the problem by taking the antenna off the mount. Please advise.
Jim202
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Re: 2014 Dodge Ram RF problem

Post by Jim202 »

niagara16 wrote:We have installed several motorola PM1200 radios into 2014 2500/5500 Dodge Rams. The problem is no matter where place the antenna RF seems to get into the dash board, Trailer brake system and computer. Before pushing this off to dodge and a shield problem of there cables i am looking for ideas to try. I have tryed mag mnts that go all the way back to the rear bumper. I have only solved the problem by taking the antenna off the mount. Please advise.

Your not providing much information on what the problem is.

Is the dash indicators going out, flashing, giving wrong indications, shutting off engine, brakes being applied?

Does this happen when the radio is in receive or transmit?

Just for grins and giggles, have you tried a different radio model?

Give us a hint on what you think is happening.

Jim
niagara16
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Re: 2014 Dodge Ram RF problem

Post by niagara16 »

Cause check engine light to come on, makes trailer brakes come and trucks runs rough. Only when radio transmits
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PhillyPhoto
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Re: 2014 Dodge Ram RF problem

Post by PhillyPhoto »

niagara16 wrote:Cause check engine light to come on, makes trailer brakes come and trucks runs rough. Only when radio transmits
Might not be the antenna. How is the radio wired for power and ground? Have you tried a different series radio since you said have the same radios in other trucks? Have you tried a radio outside of the vehicle hooked up to it and see if it still causes the issues?
niagara16
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Re: 2014 Dodge Ram RF problem

Post by niagara16 »

It is only the 2014 dodge rams. Change the freq by 6 mghz no problem. Today I going to wrap tin tape around ant cable. The power is to the battery. Ign cntrl is to a relay. Relay is ran to battery and ign cntrl part to factory power point. Ground is a chassis grnd.
Garyf629
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Re: 2014 Dodge Ram RF problem

Post by Garyf629 »

Sounds like RF is getting into the trucks computer. Make sure the radio is not mounted, or the antenna cable is not run near the computer. I always run isolaters on the power lines. Check and make sure that both the computer & radio are well grounded. Move the radio as far away from the computer as possible and try it again.
niagara16
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Re: 2014 Dodge Ram RF problem

Post by niagara16 »

Radio is mounted on rear vehicle floor under seat
Garyf629
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Re: 2014 Dodge Ram RF problem

Post by Garyf629 »

Where is the antenna? I once had a Fire Chief that insisted on a left front fender mount antenna, which was right above the trucks computer. Everytime he keyed the radio, the passenger side window would open, and the ABS would go off.
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Bill_G
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Re: 2014 Dodge Ram RF problem

Post by Bill_G »

niagara16 wrote:It is only the 2014 dodge rams. Change the freq by 6 mghz no problem. Today I going to wrap tin tape around ant cable. The power is to the battery. Ign cntrl is to a relay. Relay is ran to battery and ign cntrl part to factory power point. Ground is a chassis grnd.
RF clobbering vehicle electronics is common, but being frequency specific is not. The fact that you can place the antenna anywhere on the vehicle supports the idea that it is the freq that is the culprit. You could test this further by keying a portable radio on the same channel near the vehicle to see if you get the same result. If that proves true, you need to work with Chrysler to find a solution. Shielding will not help. It's an unlucky find, and the ultimate solution may be returning those trucks for a different model. However, the customer and Chrysler will make the determination. Stop the installs, notify your supervisor, and let the top brass figure out the best course of action.
jmfirefighter20
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Re: 2014 Dodge Ram RF problem

Post by jmfirefighter20 »

I'm going to be doing an install of a 100 watt VHF APX in a 2014 Ram 1500. Antenna is going to be mounted on the roof.

My 100 watt VHF astro spectra in my Jeep, with the antenna mounted to the rear, dosen't seem to have any ill effects on the CAN bus or computers in it.
Joshua
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escomm
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Re: 2014 Dodge Ram RF problem

Post by escomm »

jmfirefighter20 wrote:I'm going to be doing an install of a 100 watt VHF APX in a 2014 Ram 1500. Antenna is going to be mounted on the roof.

My 100 watt VHF astro spectra in my Jeep, with the antenna mounted to the rear, dosen't seem to have any ill effects on the CAN bus or computers in it.
PM1200s are lowband. With a frequency difference of over 100MHz I don't think there is an apples to apples comparison that can be made here.
jmfirefighter20
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Re: 2014 Dodge Ram RF problem

Post by jmfirefighter20 »

escomm wrote:
jmfirefighter20 wrote:I'm going to be doing an install of a 100 watt VHF APX in a 2014 Ram 1500. Antenna is going to be mounted on the roof.

My 100 watt VHF astro spectra in my Jeep, with the antenna mounted to the rear, dosen't seem to have any ill effects on the CAN bus or computers in it.
PM1200s are lowband. With a frequency difference of over 100MHz I don't think there is an apples to apples comparison that can be made here.

Yes, there is a difference between Low band and VHF, but RF is still RF. I wasn't comparing apples to apples and nowhere does it say in my post that I am. Who's to say that there wasn't a design change in the 2014 model year? Jeep and Dodge are built by the same company and share many parts/wiring/etc between the two. I was mentioning it because of the fact that I will soon be doing a radio install as well, and will advise if I have any issues. Perhaps it could be more than just a Low Band versus VHF issue. It seems like they're having problems with more than one truck.

Oh, and I'm installing a low band in the same truck as well.

This is a pertinent thread to my future build next week, and I was offering a simple comment. No need to jump down my throat as if I have no idea of the difference between Low band and VHF.
Joshua
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GroundRat
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Re: 2014 Dodge Ram RF problem

Post by GroundRat »

The fact that you can move the antenna to the rear bumper and it still happens leads me to believe that there is an issue under the hood or in the cab.

Route ignition power straight to the battery and key up - does the issue still exist?
Put a new antenna on it and key up - does the issue still exist?
Does the radio display go dim when you PTT? There could be a short somewhere in the install if it does.

Good luck! Tracing issues is always fun!
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Bill_G
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Re: 2014 Dodge Ram RF problem

Post by Bill_G »

He said in his second response that he can go to a chan that is 6mhz away, and the problem doesn't occur. I think we all agree it's the transmitter getting into one of the vehicle braincells, but it's not the xmit power like is usually the problem - it's the frequency. It's probably very close to the clock freq of the uP, or a harmonic of it, causing that module to burp. They could try turning the power down 6db to see if that helps. I doubt it will, but if it appears to fix the problem, I wouldn't do it as *the fix* because the problem could reoccur down the road someday after a truck tune up, or the radio gets replaced.

And since it affects the brakes, I would walk away from this until the customer, the dealer, and the OEM have a Come to Jesus Meeting agreeing on some course of action.
Jim202
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Re: 2014 Dodge Ram RF problem

Post by Jim202 »

Bill_G wrote:He said in his second response that he can go to a chan that is 6mhz away, and the problem doesn't occur. I think we all agree it's the transmitter getting into one of the vehicle braincells, but it's not the xmit power like is usually the problem - it's the frequency. It's probably very close to the clock freq of the uP, or a harmonic of it, causing that module to burp. They could try turning the power down 6db to see if that helps. I doubt it will, but if it appears to fix the problem, I wouldn't do it as *the fix* because the problem could reoccur down the road someday after a truck tune up, or the radio gets replaced.

And since it affects the brakes, I would walk away from this until the customer, the dealer, and the OEM have a Come to Jesus Meeting agreeing on some course of action.



There is the issue of safety here and the dealer needs to get on the horn to the plant engineers to look at the problem of the electrical computer system being too prone to RF signals causing problems.

My bet is there is no RF bypassing and no RF chokes or ferrite cores on any of the inputs to the brains in the truck. The engineers took the short road and probably didn't do much testing in this area. So now they will have the chance to take a close look at a reported problem. If they don't there is more clout that can be brought to bear.

Jim
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Bill_G
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Re: 2014 Dodge Ram RF problem

Post by Bill_G »

Jim202 wrote:
Bill_G wrote:He said in his second response that he can go to a chan that is 6mhz away, and the problem doesn't occur. I think we all agree it's the transmitter getting into one of the vehicle braincells, but it's not the xmit power like is usually the problem - it's the frequency. It's probably very close to the clock freq of the uP, or a harmonic of it, causing that module to burp. They could try turning the power down 6db to see if that helps. I doubt it will, but if it appears to fix the problem, I wouldn't do it as *the fix* because the problem could reoccur down the road someday after a truck tune up, or the radio gets replaced.

And since it affects the brakes, I would walk away from this until the customer, the dealer, and the OEM have a Come to Jesus Meeting agreeing on some course of action.



There is the issue of safety here and the dealer needs to get on the horn to the plant engineers to look at the problem of the electrical computer system being too prone to RF signals causing problems.

My bet is there is no RF bypassing and no RF chokes or ferrite cores on any of the inputs to the brains in the truck. The engineers took the short road and probably didn't do much testing in this area. So now they will have the chance to take a close look at a reported problem. If they don't there is more clout that can be brought to bear.

Jim
I can't speak for Chrysler, but I did work for (acronym) and (acronym) at different times as a sub-contractor (signed one of those ndf things), and both had test chambers that they blasted RF at production vehicles to check immunity. You could very well be correct, but I still think because of the specificity of the problem, this customer has found the fickle finger of fate by operating on the one and only freq that passes. If the OP cannot find a portable on this channel to test with, he could try keying another vehicle adjacent to this one to see if he gets the same results. Channel X clobbers the truck, and Y doesn't. Same power out, different freqs. If he can't duplicate the problem, if he gets different results, then he needs to do more troubleshooting.
dbartkowiak
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Re: 2014 Dodge Ram RF problem

Post by dbartkowiak »

I read through the thread and noticed no mention of the measured VSWR. I have experienced the same problems in different vehicles and in most, but not all cases, a high SWR caused the vehicle problems. I guess all that reflected power wants to go somewhere if its not going to be radiated.

I also noticed in the initial post that you used a mag mount. Was that just to test different locations or is that the intended antenna installation? I have found low band antennas to be difficult to tune at times and if this is one of those times, the mag mount mag be causing it or compounding it.

I'm real interested in the solution that you find. We still use low band and from time to time experience your pain.
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