alarm customer complaint

So I installed an alarm/remote starter not too long ago. I got everything working fine.....(so I thought I did.) The guy bought everything brand new and got a few accessories for it like a digital tilt switch, sonic sensor, back up battery....etc. It was a newer GM car, so I had to diode isolate the door triggers. Then I had to diode isolate each thing that is hooked up to the instant trigger wire. The first time I worked on it and finished....later on that night the guy said that the alarm keeps going off like 20 mins. later for no reason. All sensors are turned down enough (not that sensitive). So I said maybe its a bad diode or maybe I possibly installed one wrong. So I worked on it a 2nd time......changed out all the diodes and double checked the door triggers, trunk, etc.  Everything is definately right this time. After I was finished, I armed it and checked everything to make sure its working. I stood there for awhile to make sure the alarm didnt go off and it didnt. Let the guy have his car and later on that day.....same problem/story.

Now this isnt my first install. I install car audio stuff and mostly anything 12 volt. Im actually more experienced with installing alarms and remote starters. I cant even say how many ive installed....lets just say hundreds. I always test my diodes before I install them too. I know ive opened up brand new alarms and/or remote starters and had defective ones before. But it doesnt happen that much. Do you think its defective or do you think this guy is BSing me?...trying to get something for free or who knows?

Thanks in advance.

As always - AND despite our wisdom - assume it ain't bullsh. (Yeah - I know.... but sometimes they ARE right!) Maybe... RFI/EMC is triggering it... (20 minute wireless cycle?) Pssed off local is triggering it... Voltage sensing; voltage drop? An elephant changing sides every 20 minutes.... And chances of 2 faulty diodes is 1 in 100.....0000 whatever, but it is still there. And that figure was when quality existed. (These days having 10 diodes with failed rate of 1:100 means most installs will be faulty!) But you test, and chances of a soon-after failure in short-mode (but if they are of the same batch...) Though I suspect it isn't the diodes. For "real" experience (and model specifics), others can advise. Best wishes!

oldspark wrote: RFI/EMC is triggering it... (20 minute wireless cycle?) !

What does this mean? Can you explain more?

Is it possible that ill need to install a relay at all?

I just meant outside electrical interference. Maybe a 20-minute polling system (especially if GSM!); or surveillance system; Omega base; etc. Certain GM-H vehicles here are known not to open or start when parked at a certain sports stadium; outside chemists (drugstores) etc. Ironically it's one of their "top of the line" sports/SS models! Though RFI(EMI)/EMC bleed through etc is different. The TLAs are Radio Frequency (& Electro-Magnetic) Interference & Electro-Magnetic Compatibility. I wondered if stateside was less experienced with GSM, but its shielding requirements are well known - stateside merely lags the brain-tumor & cancer count LOL! Anyhow, that's all part of the fun fault finding phase. Depends on where it is parked? Time of day? Weekday? Or a hairline crack in a fuse that causes you to sell your prestige car in frustration? (Rule #1 - rotate all fuses and break/make connectors.)

Telling us the year and model could help....Mike M2

Tech Manager

CS Dealer Services

Don't worry Mike and Peter, he posted another the same and hopefully I've answered his problem, H.