TOPIC: Do old fuses& Relays effect Computer function?

So Don Andersen posted to his thread MPG Vortec 5.3 (00-02) 2 days ago, telling of how he replaced 2 fuses. One of the fuses was I believe for the computer (PCM, ECM, etc.) that governs the engine. OK. Last week a freind who owns an '89 Nissan Maxima asked me to replace several power relays and several fuses. She said some of these items would effect engine function (my words not hers,but that's what she meant). I have always just taken fuses and relays for granted--if they aren't blown or fried, and they work, they work, right? Well, none of the original fuses/relays were dead, but I replaced them anyhow. Guess what...the random idle roughness and overall driveability IMPROVED markedly on this car. I had previously gone through the procedure to "pull" the codes from this car's computer (not too straightforward there's 5 different levels of codes w/ this pup) and found no codes.


So now Don posts about replacing 2 fuses on his Vortec 5.3, it sounded to me like Don had a similar experience.


Perhaps relays wear and fuses get oxidized, increasing resistance to current flow. Inviting in Poltergeists, goblins, etc....? Increasing electrical resistance in general, this puts more strain on charging system, and could make sensitive curcuits (i.e. computers) tweeky.



Anybody have any thoughts/input about this. Is this common knowledge I've somehow missed? What say the Computer specialists out there...?



Thanks!!

TracyG Gadgetman Reno

Hi all,

There may be a lot to this idea, my '07 Avalanche has about 55,000 miles on it right now. The 06/07 Avalanches, Escalades and Suburbans have a history of odd occurences at the 50,000 mile window.

More specifically, the sequence of events that occurs is the ecu puts up a message that a failure has occurred with the traction control system and that it has disabled it. The next thing that happens is the ecu reduces the power of the engine (possibly to prevent an accident on slippery roads?). If you ignore this and attempt to drive the vehicle home it reaches a point where the ecu has almost completely disabled the engines ability to function. When this happened to me I thought the engine was going to drop on the ground, that is how bad it was running.
I got it into a parking lot and shut it down, did some checks, restarted it and was able to drive it home. This hasn't happened since but the traction control message has popped up a few times. This is a known problem for these vehicles but GM has no specific answer. I think I am going to invest in some fuses this week.

Karl Fortner
Tacoma, Washington

Hey Karl, new fuses sure can't hurt, only a few $$ to change 'em. Be interesting to see if this gives any real result. It's a bit spooky to me at least to think what if this fuse/relay issue is a ghost in the Machine, been under our noses all this time:huh:...


I'm sure you will let us know what you observe! Thanks, Karl!


TracyG Gadgetman Reno

OK, I just re-read everbody's posts on the MPGVortec 5.3 thread. It could be that by simply pulling/re-inserting fuses the scraping action on contacts is forming newer connections. IT seems common sense to me that any slight oxidation on the metal surfaces gets disturbed by mechanical action. While its hard to see, down at the molecular/atomic level the scraping action might be like a bulldozer moving material around...


Also pulling a fuse or relay causes an open circuit, this might help effect a "re-boot" for the computer.


So either replacing w/ new or just R/R the existing fuse or relay might be worth remembering for our "trick bag".


Just me thinking out loud!

TracyG Gadgetman Reno

I think I'm going to get a can of contact cleaner as well!!!

Just because

Karl Fortner
Tacoma, Washington