ECU (fried?)
I didn't see a thread on this, but here is my questions, I was having issues with my display along with the radio, so I was reading thru threads to see what I could do and one of the threads said I should replace the battery so I did, now the bad thing is I put an optima yellow top in my car, but the old battery and the new battery were different, the positive and negative where switched, so I put on the terminals like I had the old battery and my car went crazy, I thought it was the viper car alarm system so I had a guy come out and check, and he said I switched the terminals and put them on backwards, I told him that I didn't know battery's switched like that, but long start short he said I could of blew my ECU so I went and got a new battery that fit with the terminals now, and the car won't start, I get power, but it won't turn over, so I bought a OBD2 and hooked it up and it's saying it won't connect to the car, I tried it on my Mazda 6 and it connected to the car, so my questions are is it the ECU? I replaced all fuses already and if it is the ECU where can I get one for a M/T?
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First, start checking every fuse and relay. There are two banks of them, one in the driver's footwell kick panel and the other in the engine bay just behind the driver's side headlight.
Validate that all fuses and relays are good, nothing melted. Next, have your starter tested OFF the car. If they are all good then yes, you most likely fried your PCM (ECU). Expect a huge bill if you have a dealer replace it. If you manage to find one somewhere else, make sure it's the right part number for your specific trim/transmission/etc... You will still need the dealer to sync it up with the rest of the modules properly. Also possible you damaged one or more of the other electronic modules in the car. I recommend paying attention to battery terminal markings in the future. |
Originally Posted by RIWWP
(Post 4450768)
First, start checking every fuse and relay. There are two banks of them, one in the driver's footwell kick panel and the other in the engine bay just behind the driver's side headlight.
Validate that all fuses and relays are good, nothing melted. Next, have your starter tested OFF the car. If they are all good then yes, you most likely fried your PCM (ECU). Expect a huge bill if you have a dealer replace it. If you manage to find one somewhere else, make sure it's the right part number for your specific trim/transmission/etc... You will still need the dealer to sync it up with the rest of the modules properly. Also possible you damaged one or more of the other electronic modules in the car. I recommend paying attention to battery terminal markings in the future. |
Also the only fuses that got blown were the 15a engine and the interior audio fuse
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Get a multi-meter and test the continuity between relay prongs. You are going to have to do some research on what you need to be looking for on each relay. If you know the 12v side of a relay, you can also test that with the car battery to make sure it functions properly.
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Replace those two fuses before digging into anything else. The engine fuse itself will prevent you from starting, and may be your entire problem.
That couple cent fuse may have saved you several thousand bucks. |
dont forget about the mains fuse, 120A and underneath the mains harness at the fuse box ... easily missed.
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Originally Posted by RIWWP
(Post 4450776)
Replace those two fuses before digging into anything else. The engine fuse itself will prevent you from starting, and may be your entire problem.
That couple cent fuse may have saved you several thousand bucks.
Originally Posted by paimon.soror
(Post 4450781)
dont forget about the mains fuse, 120A and underneath the mains harness at the fuse box ... easily missed.
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Originally Posted by paimon.soror
(Post 4450794)
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Originally Posted by paimon.soror
(Post 4450813)
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if the car has power then the 120A fuse is fine.
with the engine fuse replaced the car still does the same thing? does it crank at all? "turn over" means different things to different people. |
Originally Posted by Karack
(Post 4450821)
if the car has power then the 120A fuse is fine.
with the engine fuse replaced the car still does the same thing? does it crank at all? |
check the BTN fuse specifically and also the starter motor as described by RIWWP. i would also check the engine fuse again.
(i realize you already replaced all the fuses but a short caused by the reversed battery may be blowing the new fuses) |
Originally Posted by Karack
(Post 4450829)
check the BTN fuse specifically and also the starter motor as described by RIWWP. i would also check the engine fuse again.
(i realize you already replaced all the fuses but a short caused by the reversed battery may be blowing the new fuses) |
Well if you are having a can bus issue and the fuses are good then you have serious issues. You need to get it properly diagnosed by a qualified technician.
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Originally Posted by 9krpmrx8
(Post 4450848)
Well if you are having a can bus issue and the fuses are good then you have serious issues. You need to get it properly diagnosed by a qualified technician.
since nothing works inside the car the datalink issue might be first on the list to go after. normally the cigar lighter fuse powers the datalink also but don't quote me on it in this case. i would simply check all the new fuses again. |
my mistake, missed the part where you were getting some power to the vehicle.
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Is the "engine " small fuse good?
What lights up in the dash. Got a feeling this is going to be a real puzzle......hope not though. Can bus issues in these cars are a black art. |
Originally Posted by olddragger
(Post 4451023)
Can bus issues in these cars are a black art.
but module failures are relatively uncommon, i'm betting it's just a short somewhere that keeps popping fuses. which even that can turn into a nightmare quite quickly. |
Originally Posted by Hemp6473
(Post 4450824)
but I can't roll any windows down, sun roof, locks, heated seats anything
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you got the wrong battery. I had redtop and now Yellow top. what reversed terminal. I'm so surprised that people can be so retarded and get the wrong battery.seriously wtf ?
check everything and hope for the best. |
Originally Posted by nycgps
(Post 4451166)
you got the wrong battery. I had redtop and now Yellow top. what reversed terminal. I'm so surprised that people can be so retarded and get the wrong battery.seriously wtf ?
check everything and hope for the best. |
for those who cant read, it means do NOT believe whatever the parts guy(nor their computers) tells u, lots of time they are wrong. u got the wrong battery cuz it probably told u a 24r or 34r will work, its wrong. most if not all japanese cars uses group 35 size battery.
another example is, when i tried to fix my 1991 fc that has a broken condenser for god knows how long, got most parts and needs a new drier(for those who dunno, drier on rx8 is part of the condenser assembly not a separated part), checked all local az/aap/etc, they listed the wrong drier, first i told the parts guy its wrong, the parts guy looked at me like i know nothing and assures me that its right, just to embarrass the shit out of him i told him to go ahead and order it. couple days later the part came, its wrong obviously, i took my old drier there and said "what part of this drier is the same as the drier u said is right? " he act stupid and was like no way hose. i told him exact what to order and another couple days later the right part came. /storyends so yep, do ur own research b4 ur buy ur next part |
i'm quite sure he realizes that already, instead of continuing to point out the obvious we could perhaps try to help?
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guess so, sad im nowhere close, happy to help
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OP, is your Alarm standard OE, or aftermarket?..
If you are not sure PM me your full VIN Number and I can check. |
Originally Posted by 9krpmrx8
(Post 4450848)
Well if you are having a can bus issue and the fuses are good then you have serious issues. You need to get it properly diagnosed by a qualified technician.
Originally Posted by olddragger
(Post 4451023)
Is the "engine " small fuse good?
What lights up in the dash. Got a feeling this is going to be a real puzzle......hope not though. Can bus issues in these cars are a black art.
Originally Posted by Harlan
(Post 4451063)
This is not a computer issue, check to see if power is available to your foot well fuse box. Also recheck the fuses down there. If no power is available then check at the main fuse box, it's probably the accessory fuse, but I'm too lazy to look it up. Somehow you are missing a substantial amount of power to accessories and when you fix that, everything else might work too.
Originally Posted by nycgps
(Post 4451166)
you got the wrong battery. I had redtop and now Yellow top. what reversed terminal. I'm so surprised that people can be so retarded and get the wrong battery.seriously wtf ?
check everything and hope for the best.
Originally Posted by ASH8
(Post 4451239)
OP, is your Alarm standard OE, or aftermarket?..
If you are not sure PM me your full VIN Number and I can check. |
Originally Posted by Hemp6473
(Post 4451390)
It's a viper car alarm system |
I go alarm first before anything else then.
BTW: As I said some 2004's had no factory Alarm: Only OE Immobilizer. If it had a factory system then why would a Viper also be fitted. |
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Ok. Pulled the main 120a fuse out and it was broken so now I can't find anyone with this fuse , advance auto, autozone, didn't have any at all and now I'm online looking for this fuse and can't find it, I wish I could post a pic on here to show you, I'm going to try and see if this works but none look like this at all, but here goes....
Don't know if they uploaded to this or not |
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Some more
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Last one
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maybe you will be good then---x fingers for you.
http://www.google.com/url?sa=t&rct=j...tsHNrzD6bBim7A |
either get one from the dealer or an auto parts store(if not from the dealer bend the flat fingers out and you may have to grind the holes to match).
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I saw this one idk if this matters or not
2 Pcs Gold Plated Fuse 120A 120 AMP for Auto Car/Boat/Truck Audio 80x22mm-in Other Electronic Components from Electronic Components & Supplies on Aliexpress.com |
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If that doesn't solve your problem, then check the Viper module as it will have a starter kill function. So if its not operational and unarmed the car won't start. Or you can simply short out the bypass by reconnecting your starter wire at the ignition, I believe it's purple but I'm not entirely sure.
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if I were u I will just remove the Viper alarm.
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I would jump 12V to the starter directly to ensure the engine even fires, for that matter.
With electrical problems all the talk in the world is irrelevant, just have to get in their and start eliminating possible causes. One item at a time. |
Originally Posted by Carbon8
(Post 4451989)
I would jump 12V to the starter directly to ensure the engine even fires, for that matter.
With electrical problems all the talk in the world is irrelevant, just have to get in their and start eliminating possible causes. One item at a time. |
Relays aren't dependent on polarity, fix the alarm first.
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Originally Posted by Carbon8
(Post 4452049)
Relays aren't dependent on polarity, fix the alarm first.
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As you have been told the RX-8 main fuse 120 Amp is Mazda part number F151-67-099.
It is also used in ALL RX-8's , ALL NC Miata/MX-5 and Tributes 2000-2003....you may find Ford Explorer of that era also has same main fuse. |
M8 you really are not listening to previous comments, in most cases (9 out of 10) like this are after market alarm systems, either poorly installed originally, or they have their own quality/reliability issues..
Repeat what someone else has said, IF you can completely isolate your Viper alarm do so, and then check if engine will fire, windows etc.. Eliminate one thing at a time.... ;) |
Until you sort out all your fuse/power issues I wouldn't start pointing fingers at the aftermarket alarm system. The immobilizer has several components that all are fed by different fuses and all need power for the car to start. I searched for Immobilizer fuse and found a couple threads, here's one that sounds identical.
https://www.rx8club.com/trouble-shoo...rnator-234962/ If you still have the problem after replacing the main fuse get a multimeter and check for power at the fusebox and check for continuity on each fuse. When all your accessories have power and the thing still won't start you can rip out the alarm system. Otherwise you just risk disabling the car in a new way by removing the alarm system wrong. |
well he actually needs to get the 120A circuit fixed first, that feeds power to virtually the whole car and i can guarantee it won't start with it removed or blown.
mazda probably carries that fuse in stock, a trip to the wreckers would probably also yield something from another vehicle with the same configuration. but it does boggle me that the huge arcs weren't an indicator of a problem. i've never even blown a main fuse because it's like welding when you try to connect a battery backwards and quite difficult to blow that circuit. i hooked up the battery backwards in my 7 the other day(battery relocated to the bins and can easily fit forward or backward) because i only drive it 2-3 times a year and i still wasn't able to blow the 80amp fuse. |
u have a 120amp fuse popped and u not gonna replace that first?
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I'm gathering he's figured that out and just needs to find one.
Nothing like a good cliff hanger. http://www.diabetesmine.com/wp-conte...05/popcorn.jpg I'm a fatal optimist, except for when I'm not. I hope its just the fuse. |
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