is this possible, alarm burn pcm?

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t&t tech

Platinum - Posts: 2,608

Joined: October 05, 2008

Location: Trinidad and Tobago

Posted: April 01, 2009 at 4:49 PM / IP Logged

ok so here's the deal, installed a 791xv into a 2005 subaru impreza recently, foreign used i might add, no factory immobiliser, pretty straight forward as i've done lots of them before, no problems, the customer comes back about a week after says his engine check light is flashing intermittently, so i check it out, it's off to his surprise, he says ok, drives off, calls the following day says it's on constantly now, so our supervisor is friendly and decides he'll have it scanned for them just to satisfy their claim that the alarm is causing this, we sent in the car to two of the most reputable dealers we know, scanned by both dealers and they said something was mal-functioning with the car's PCM, so now they carried it to their own guy, because apparently they didn't trust the guys we had the car done by, the car is driving all this time i might add, the guy there did his checks and said the PCM is burnt, and says the alarm caused this, the car couldn't start at this point, then he says he changed a fuse he had found to be burnt and the car started ran and then stopped again, and now they want the shop to pay for a new PCM, the guy says the wrong ignition wire was powered which caused this failure, now here is my question, is it possible the alarm could have caused this?, if so how?, the car has two ignition wires common at one point by the way and everything worked flawlessly at the shop, and how is it that even though the PCM was burnt he replaced a fuse and it started back up?, is this possible?, i'm thinking co-incidence, do you guys smell something fishy like i do?, if anything is unclear please let me know.

howie ll

Pot Metal - Posts: 16,466

Joined: January 09, 2007

Location: United Kingdom

Posted: April 01, 2009 at 5:47 PM / IP Logged

The warning light as far as I know should have come on IMMEDIATELY had you done something wrong. May I assume you did a before and after vehicle check? If so you shouldn't be liable, does your company have any friendly relationships with Scubie dealers over here (UK) or in Florida. I have had one VW and one Vauxhall give me grief, bad running and stalling out after I connected the tach feed to an injector wire, I replaced with an inductive sensor and no further problems. It sounds like someone is trying it on.

t&t tech

Platinum - Posts: 2,608

Joined: October 05, 2008

Location: Trinidad and Tobago

Posted: April 01, 2009 at 6:56 PM / IP Logged

yes i did a before and after check howie, and i didn't even use tach, voltage all the way, and what i don't get is how could the pcm be burnt and the car started and ran, the thing is he said it firstly only came on while he was driving, which leaves me wondering if it was that way before he came inthe shop, because i would have no way of knowing this unless i drove the car before i installed.

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 01, 2009 at 9:58 PM / IP Logged

There is an easy way to tell.

Have the car fixed (at customers expense).

Have the dealership disconnect the wire they "think" caused the problem. After a week or so of driving the car hook the suspect wire back up.

If the PCM fails again you reimburse the customers for the first (and second ECU).

It's definately a gamble, but I think you'll come out ahead.

Kevin Pierson

tedmond

Gold - Posts: 4,610

This member has been recognized as an authority in Mobile Security and Convenience. Click here for more info.

Joined: January 06, 2007

Location: Ontario, Canada

Posted: April 02, 2009 at 6:54 AM / IP Logged

that is true, if something did go wrong, it would have thrown a CEL light. if the pcm was damaged, how could that person still drive? but in your case, i would suggest doding what kevin said. it may cost now, but at least you took the time to take care of the customer. its always customer appreciation that makes a shop reputable.

howie ll

Pot Metal - Posts: 16,466

Joined: January 09, 2007

Location: United Kingdom

Posted: April 02, 2009 at 7:02 AM / IP Logged

Run with KP's suggestion.

KarTuneMan

Platinum - Posts: 7,056

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Joined: December 14, 2004

Location: Isle Of Man

Posted: April 02, 2009 at 7:44 AM / IP Logged

KPierson wrote:

There is an easy way to tell.

Have the car fixed (at customers expense).

Have the dealership disconnect the wire they "think" caused the problem. After a week or so of driving the car hook the suspect wire back up.

If the PCM fails again you reimburse the customers for the first (and second ECU).

It's definately a gamble, but I think you'll come out ahead.

GAMBLE? This word don't even come close ... the suspect wire is hooked back up and you get toast again? I would be scared poopless!

(it is however, the best way to investigate and solve the issue!) good luck and keep us posted.

t&t tech

Platinum - Posts: 2,608

Joined: October 05, 2008

Location: Trinidad and Tobago

Posted: April 02, 2009 at 4:55 PM / IP Logged

here's the thing, the customer doesn't want to go with the dealers we reccomended, they wanna go with their guy, who is a side of the road electrician, who was changing oil in a nissan 280c when we went to check out the place, i was like wth, so the guy originally says, we connected the wrong ignition wire, the vehicle mind you, only had one, so now he changes the theory, and says the 791xv sent a surge that fried the pcm, and we still have to pay, they refuse to believe that the alarm isn't responsible, taking a gamble with the pcm, that's a costly gamble, the cost of one is a little over 5k,

KPierson

Platinum - Posts: 3,527

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 02, 2009 at 5:31 PM / IP Logged

Power inputs don't "create" power surges, let alone repeated power surges over the course of days that eventually kill PCMs. Modern day PCMs are designed to handle any abuse an electrical system can throw at them, INCLUDING "crowbarring" the battery for extended periods of time. If the PCM was fried from a power surge the car alarm would be toast also.

The PCM cost 5k what (I'm not familiar with the currency in T&T)? I know that can't be US dollars. You should be able to get one for $3-400US I would think. It is a gamble, but like I said I don't think you did anything and when comparing $400 to $800 it's really not that big of a gamble.

What kind of fuse is on the power lead of the alarm? Was it blown? If there was somehow a power surge that fuse would have been blown and the alarm wouldn't work.

What fuse was blown that they replaced?

I'm not sure how things work where you are but here we always had the right to let one of our experts inspect the car and diagnose the issue. This really, really, really sounds like an unfortunate coincidence to me.

Kevin Pierson

t&t tech

Platinum - Posts: 2,608

Joined: October 05, 2008

Location: Trinidad and Tobago

Posted: April 02, 2009 at 6:06 PM / IP Logged

the alarm was still functional when i went to visit the vehicle, locks and everything, except the remote start, since the car wasn't starting with the key, i'm not sure which fuse had been changed because i wasn't present at the time, but if if the pcm was burnt, how then could replacing a fuse result in the car starting, which is what the electrician said happened, isn't a burnt pcm gonna result in an undriveable car, and currency it's like 1u.s dollar to 6 t.t dollars kevin

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