RFI Generated by Chevy Colorado Trucks

[Kriwoam]

I thought I’d ask the question here to see if anyone else has seen this, and or a possible fix.
Our fleet has 100’s of Chevy Colorado trucks from 2017-present. All of them, at least the 10 we have, some worse than othersemit terrible wide band RFI. On some trucks the FM radio is really bad till you turn off the truck.

Our 150-174 and 217-221 MHz equipment is hammered by this. I’ve seen the noise floor go up to -100 at times in the 217 MHz spectrum area. In cases, the RFI will effect other radio equipment up to 10’ away.

Because these are fleet maintained vehicles, the frown upon us pulling fuses and connectors to find the source. With a new 220 MHz DMR system on the way, there is panic setting in.

Let me know what you’ve seen or heard

thanks,
Tony

 

[12dbsinad]

Is there anything aftermarket that's been added to these vehicles? The reason I am saying this is, it is very unlikely that GM would put out vehicle that has it's FM radio wiped out by RFI.

 

[a417]

I thought I’d ask the question here to see if anyone else has seen this, and or a possible fix.
Our fleet has 100’s of Chevy Colorado trucks from 2017-present. All of them, at least the 10 we have, some worse than othersemit terrible wide band RFI. On some trucks the FM radio is really bad till you turn off the truck.

Are there vehicles w/o your fleet-added equipment to verify against? It could be a byproduct of the install that is causing that...

I'd take those back to the dealer and say "the FM radio doesn't work", see where that gets you.

 

[TampaTyron]

Time to get a spectrum analyzer (or SDR) and a loop antenna and go hunting.......... is it worse with engine on/off? Does it get better with key off or does it get better after 1-30 minutes of truck being off? Disable all of the aftermarket stuff and test. Keep in mind that truck off and cold is a different environment that running, key in accy position, and key out, but modules still running until they time out at 1-30 min after truck is stopped and key is removed. TT

 

[Kriwoam]

These are all good suggestions. The only aftermarket item is the PDU timer switch which shuts the radio equipment off after 15 min. This device is still on when the key is off, so not the source.

When two way radios were tested, I did the basic effective sensitivity test, so a 50 ohm load vs the antenna. Noise is radiated, not getting into the radio via power. The noise is there with the key on, engine running or not. The FM radio issue severity is different from truck to truck. On some vehicles, hitting the breaks will desense the FM radio.

As far as the noise in the 217-221 band, it’s level varies depending on truck temperature and possibly other things the truck does. I tried the sniffer probe method, and the vehicle wiring harnesses all radiate like a big antenna. I know the next steps are to pull fuses and see what modules are causing this, but easier said than done. Our Transportation Dept rules the show, we are just the radio maintainers. This will take some work.

So at this point, i’m interested if anyone has seen what I see, and the cause being anything other than after market equipment. I went through a similar situation with a International diesel injector system in their 2001 trucks. Took forever to get factory support with mediocre results.

Thanks for you comments so far,

 

[RFI-EMI-GUY]

"Our Transportation Dept rules the show, we are just the radio maintainers. "

I am sure if you installed a NEW radio that operates in a way that the vehicles would not run they would be giving you a call. It is same thing, their new fangled trucks are messing with communications.

 

[12dbsinad]

If that's the case I'd send about 10 trucks to the dealership with the complaint of the FM radio not working well when you hit the brakes, or when the key is turned on. Throw the problem on them first, because I'm sure whatever wideband noise is killing the FM is killing the 2 way as well. If the trans dept won't let you touch anything then I'd personally just wash my hands of the problem and let them deal with it if they know it all.. besides, the radio itself is working properly and you are the "maintainers".

 

[RFI-EMI-GUY]

True, tell them the good news is that the radios receive fine. The bad news, the trucks transmit fine as well.

 

[speedway_navigator]

Did the trucks come from Chevy or the set of Poltergeist II?

 

[sfd119]

This is a very common problem with newer GM vehicles. My 2014 has the same issue and from all the other people complaining about it, there is still no resolution. Even the factory FM radio is a lot weaker than my 2008!!

 

[KK6ZTE]

Do you have LED interior lighting or do the trucks have an in dash display?

My 17 Explorer radiates and gets into the audio amplifier when the display is dimmed (not at full brightness).

 

[devicelab]

I wonder if it's the fuel pump. I've heard those created some RFI havoc in the past. LED lighting is a good bet too. Heck, you need to give the ECU a good sniff as well. Also check for any ground connections that have come loose.

 

[tvengr]

hitting the breaks will desense the FM radio.

Are the vehicles equipped for trailer brakes? That could be an addition.

 

[krokus]

Have you setup a spectrum analyzer?

If the vehicle maintenance people will not let you pull fuses, then have one of them pull the fuses. (One call to get the fuse pulled. Another call to get the fuse replaced. Yet another call to get the next fuse pulled. Then another call to get that fuse replaced. Repeat as needed, until they get over themselves, and let you pull fuses related to your job.)

 

[Hit_Factor]

My 17 Explorer radiates and gets into the audio amplifier when the display is dimmed (not at full brightness).

Pulse Width Modulation (PWM) is common with LEDs.

 

[lr60]

2015 Colorado: I had significant interference from DMR handhelds into the truck's radio. Even with the truck radio turned off, it would get into the speakers. I bought a whole bunch of ferrite beads to put on whatever wires I could find. I finally solved it by installing an external antenna that was well grounded.

 

[KC8QVO]

When two way radios were tested, I did the basic effective sensitivity test, so a 50 ohm load vs the antenna. Noise is radiated, not getting into the radio via power. The noise is there with the key on, engine running or not. The FM radio issue severity is different from truck to truck. On some vehicles, hitting the breaks will desense the FM radio.

Can you power the radio from a battery - like a small SLA or spare vehicle battery - to do some testing?

I have had RFI in several vehicles. The best help to mitigating it I have found is grounding/bonding the exhaust pipe at the end of the truck near the rear axle.

My current truck is a 2011 F350 and, instead of tapping the pipe itself, I used a hose clamp around the last hanger arm in the rear (above the rear axle). I have a ground strap bridging that hanger arm and the frame.

The exhaust pipe is suspended by the hanger arms and rubber isolators so as to keep the exhaust system from rattling through the chassis. The down side to the rubber isolators is that they also make the exhaust system a nice antenna to freely radiate RFI generated at the engine (injectors, alternator, fuel pumps potentially, yada, yada, yada).

By electrically bonding the exhaust pipe towards the rear of the vehicle you bring the pipe system to very near the same ground potential and cut out the vast majority of it's ability to "radiate".

Think about it for a minute - if you connect a jumper wire from your two way antenna to ground, shorting it out, do you think it is going to work as well?

To try this - get a couple of C clamps or Vice Grip type pliers and a wire (thicker the better, if you don't have ground braid even a strip of 14 gauge stranded wire might work). Find a place on your exhaust pipe to clamp on to - even if it is the tail pipe tip. Connect that to ground (clean, direct metal-to-metal with little resistance - preferably the frame, not a bumper, hitch, or body panel as those are all separated from the chassis with brackets).

Another note is bonding body panels together can actually make a difference as well. Same goes for the hood over the engine compartment. Often times the hood is bonded with a ground braid by the factory, but adding additional bonding to each side by the hinges can help.

The idea is to bring as much "metal" on the vehicle to the same ground potential so it doesn't radiate.

The idea for running off the battery is to entirely separate the power sources, regardless of whether your previous test seemed to show any issues radiated or not.

 

[boy7777777777]

I used to have led headlights. When they were turned on the two way went silent. Headlights were replaced with standard bulbs. So as a previous post stated I’d look into that also.