Chris Gregg

iTrader: (59)

Car sat in parking lot idling and suddenly stalled. Car would turn over but not restart and seemed like no fire occuring. Long story short, 25 amp Engine ECU "BR fusable link" is blown. Attempted to replace, blew again immediately, even after sitting and cooling off.

I am currently reading through my FSM. I am looking at the diagnostic sections and will be testing electrical components such as the Safety Relay, ECCS relay, Fan relays, and fuel relays to start with. I will also be checking plugs to engine components which could have overheated.

Curious, I've never had this fusable link blow. I once had my O2 wire get snagged and the wires shorted, this blew the in cabin Engine Cont. fuse. So, I'm kind of at a disadvantage regarding the systems and components this fusable link is associated with.

I was hoping someone has experienced a similar problem and could help expedite the trouble shooting!

maximomo

iTrader: (2)

My 4th gen I30 was doing something like this and it turned out to be a dead cell in the battery. Try replacing the link and swapping out the battery b4 chasing other stuff.

Chris Gregg

iTrader: (59)

Thanks, but as noted above, the link was replaced and immediately blew again. Of course this only occurs when the ignition switch is on....turning on the ecu. If I remove the eccs relay, then the fuse remains intact when ign on. So, of course it is something on the ecu side of things. Battery is perfectly good, having cranked a long time on the battery and it still reads just below 12v. Also, everything on the car has full power and is functional.

I checked safety and fuel pump relays.....all good of course. Fan relays look good. Didn't check those becuase the ecu fusable link still blows even with the relays and fans disconnected.

I checked the MAF, but cannot find in the FSM any information about what the harness should read under conditions where no voltage is being applied. It only gives info about checking it under operational conditions or whether there is continuity. I understand that if there is a wire broke, then testing continuity would be the thing to do. However, I don't believe there is a broken wire, rather two wires are possibly melted together.

I checked continuity between the terminals on the MAF harness. There is 0.0 continuity between A-D, B-D, and C-D. All other tests between terminals result in a 0.5 reading. The wires A,B,and C are of concern, wondering whether any one or more of those have fused to D.

Anyone have info on what the readings between these terminals on the harness should be with no voltage applied? Anyone car to test?

Just remember, there are terminals A through E on the harness. There is a blank spot beside E. So, essentially, the plug has to be turned upside down to get A-E from left to right. The last spot on the right is empty. Thanks!

maximomo

iTrader: (2)

Are you saying that as soon as you turn the ignition on the FL blows?
OR

Does it blow when you start cranking?

If it blows when you start cranking I'd still say you should swap out the battery with a known good one. My battery measured fine. In fact, I could turn the ignition to on and jump start the starter with a screwdriver and the car started and ran perfect. BUT, if I turned the key to start the FL would blow. I forget which relay we pulled but when we pulled one it stopped blowing the FL too.

Ended up having a shop check it and they replaced the battery and the FL. Problem solved.

IT DOESN'T MAKE ANY SENSE LOGICALLY! I was even working on the car with an electrical engineer--and he still is baffled how the battery could be the cause yet work perfectly fine under full load conditions. Internal cell short is the only possibility...but who knows?

Chris Gregg

iTrader: (59)

It happens as soon as the ignition is turned on, no cranking.

I actually have installed a push button start, essentially bypassing the clutch pedal safety switch. This is actually how I moved the car around to get it towed, then moved into my garage (I know, the starter should not be used in this method...but replacing a starter is the least of my concerns!).

So, when the ign is turned to "On," no cranking......current is sent through the ecu fusable link, which then sends power through the eccs (ecu) relay. In either situation where I replace the fusable link and turn the ignition on OR when ignition is on and I install a fusable link, the link/fuse blows.

If I remove the eccs green relay, then the link remains intact while ign is in the "On" position. With ignition "On" and link installed, if I replace the eccs relay, the link immediately blows. But, for sake of arguement, I will disconnect the battery and see if I can find a 12v source to boost/supply power to the car to rule out the battery.

Chris Gregg

iTrader: (59)

Problem resolved....I believe. I knew one of the main systems had to be causing this to occur. I checked the wires under the hood and found the MAF wire was destroyed. I cannot tell if it shorted then melted or melted due to engine compartment heat and then shorted.

I had to take the harness back into the main harness off the back of the engine, so the damaged wires went that far. I had to remove about 6-8 inches of damged wire in total. The wires off the back of the engine are really close to my exhaust set up, so I think this was the source of the problem. In fixing the wire, I double heat shrinked the two wire paths in the MAF harness, and taped them up as well. Then I heat shrinked them together, taped again, then wrapped the wires in heat wrap, then put wire loom 1/2 way up the MAF harness. Of course, then I re-routed the harness further away from the exhuast. Car has started and idled fine. I've got some other stuff to work on, so I'll take if for a drive later.

Thanks to all who posted and PM'd me!

Chris