TN_Mike

Here's a weird one for you. I have a Liftmaster garage door opener at home. About a month ago, my garage door remote in the Cherokee stopped working. Changed the battery, no luck. Tried touching all the solder joints on the board in the remote with a hot soldering iron thinking I maybe had a broken solder joint, no luck there either. So I just figured I'd get a new remote. $45 later and a brand new remote and it is doing the same thing. So I start to troubleshoot deeper.

I noticed this weekend that I also have a buzz in the audio of the Cherokee's radio. Even on FM stations. Hmmmmm.....in the process of checking all this, I find out that my remote actually works perfectly, as long as the Cherokee isn't running. When the Cherokee is running, not only will my remote not open or close the door but the remote in my wife's car sitting next to the Cherokee in the garage won't either.

So, obviously I have some sort of electrical problem, more than likely a busted ground somewhere, on the Cherokee that is causing the buzz in the radio and allowing the Cherokee to generate what is probably a wide spectrum RF signal that is jamming the receiver of the garage door opener.

My question is, have any of yall heard of this or had this kind of thing happen before?

In the last year I have replaced my plugs, plug wires, distributor cap and alternator. Thinking the most likely candidate was the alternator, I pulled it this weekend and swapped it with a new one but, no luck. I doubt it could be the distributor cap, not sure about the plug wires.

Any ideas? Any advice??

Harper

Was this happening before you changed your plugs and wires? The secondary side of the ignition system is the likely culprit for generating RF interference.

TN_Mike

Nope. This was not happening before I changed the plugs and wires. In fact, it wasn't happening right after I changed them either. It started about a month after the plugs and wires got changed out.

I was thinking of changing the ignition coil out to see if that is the bad component but a new, higher end set of wires would be another possibility I guess.

Harper

I'd wait until dark and then mist the wires with water from a spray bottle and look for arcing.

Another common cause is a plug wire end that is not making good contact with the plug. It will arc inside the boot, jumping a gap from the carbon core to the metal connector on the plug. Pull the wires off the plugs and look for corroded connectors.

Something else you could do, to isolate it to a particular cylinder, is to remove the plug wire completely, one at a time, and see if the garage door works.

Also, this buzz in the radio... is it a snap, snap, snap... or bzzzzzzzzzzzzzzzzzzzzzzzz?

TN_Mike

Good advice. Thanks!

And the audio problem is a Bzzzzzzzzzzzzzz kind of buzz. Continuous and the frequency goes up and down with the RPM of the engine. And it is in AM and FM stations.....

FL Denmark

check all grounds in the engine bay. if all good, replace the compensator on the generator or if internal, add a another one over the battery.

all bzzzzzzzz'ing i have ever seen has been due to one of those 2 reasons.

good luck and keep us posted

TN_Mike

Forgive me if I don't understand. "Compensator on the generator"? Are you talking about the alternator? I replaced the alternator with a brand new one this weekend thinking that was the most likely culprit. But this did not solve the problem. In fact, it made no difference at all.

Harper

Edit:

I found this interesting tidbit on a HAM radio site:



The fuel pump... didn't think about that. Does the noise in the radio come on for a few seconds when you turn the key on? (coinciding with the priming of the fuel system)

2nd edit: I went back and reread your earlier post stating that the noise goes up and down with the engine RPM. So that kinda rules out the fuel pump.

Harper

Another thought... was the alternator that you installed brand new or reman?

Some reman shops replace only the brushes. If the diode trio, voltage regulator and rectifier bridge test ok, they reuse them. It's possible that the diode trio or rectifier is faulty in your new alternator.

There is a wealth of information on this page about RF noise: http://www.eham.net/articles/8052

xjhawk

If your plugs wires are arching inside the boots that cause a permeant carbon line on the spark plugs, it is called carbon tracking, will will see clearly a black line going down the porcelain of the plug, you need to replace all plugs and wires to fix. Also, factory and aftermarket ampliers can cause RF buzz. factory and aftermarket radio heads have built in amps on the back of the deck, you can quickly disconnect the radio, or pull the fuse to see if the garage door remote works. Good luck.

TN_Mike

The alternator was a re-manufactured one but I checked and the paperwork says they replace the rectifier when they do the rebuild. I had thought of that.

Thanks for the link tot he website!

I'm thinking it is going to be a plug wire or plus now. That really sucks. I just replaced them just a few months ago. Crap.

TN_Mike

I checked a few things last night and so far, it isn't a plug or wire. At least not the three that I checked. There is one plug that is a cast iron ***** to get to on the 2.5L 4 banger like mine. It is right behind the AC compressor. I will check that one this weekend when I can really dig into it. If it is a plug I figured it would be that one since it is hard to get to.

I will update this thread to let everyone know what I find in case anyone else ever runs into this problem.

bigvig

Well there's your problem: You have a 4 banger! Seriously though, I ran into this with a vehicle a while back. Cant remember all the specifics, but it was a complete nightmare to diagnose and correct. Good luck!

mrfajita

Not nearly as weird as my friend's truck. When we were replacing the alternators the other day, whenever we hooked the battery up, my music player on my laptop in the garage would stop playing. Unexplainable. Disconnect it and it would start playing again.

FL Denmark

sorry, im from denmark and sometimes i dont use the right words.

im talking about the alternator. there is a condensator connected in paralel to cabel going to positive side of battery and ground. if that one goes bad, it make noise. sometimes it is internal in the alternator, so you cant see it. but you can try add another one over the battery. it should be ok with a 400uF . its cheap and will help locate the problem