How to test if your ECU is bad?
11-13-2006, 08:46 PM
#1
How to test if your ECU is bad?
I've been digging around in the FSM and can't find a proceedure anywhere to indicate a faulty ECU. Is there such a proceedure? Can consult II find this out in some way?
11-13-2006, 11:03 PM
#2
Senior Member
Join Date: May 2004
Location: Vancouver, BC
Posts: 933
A failure of the ECM is rare, although one has to be "careful" (read as..... make sure you follow the FSM) disconnecting/reconnecting components during troubleshooting with the battery connected and/or checking circuits with a multimeter etc., because it can be toasted. The troubleshooting matrix on page EC 55 of the '01 FSM for example has reference to ECM replacement and if you work down through section EC there is the odd "replace ECM", usually as the last resort corrective action, and I have seen it a couple of times on TSBs I think. What makes you think your ECM is fried anyway?
11-14-2006, 12:36 AM
#3
What makes you think your ECM is fried anyway?
11-14-2006, 12:24 PM
#4
Newbie - Just Registered
Join Date: Apr 2005
Posts: 4
Originally Posted by monty31
If you search "P0505" in depth, you will find that some of the people had to get their ECU replaced. Apparently, in some cases, when the IACV valve goes out, it shorts something in the ECU. I just replaced my IACV, tried to perform idle relearn and am still getting the P0505 CEL. ECU replacement is the last possibility concerning the IACV troubleshooting in the FSM, but I think I've exhausted all other options...
Could you please outline the idle relearn proceedure you tried? I was not able to get it to work on mine.
Mine is a 2001 and it seems that the proceedures I've seen on this site don't seem to work on it. I tried the ECU reset that is listed here but it doesn't seem to work on the 2k1. Is it just for 2k2 and later? I have a 2k3 G35 and the ECU reset proceedure worked on it (same proceedure) so I know that I at least am performing it correctly
11-14-2006, 02:50 PM
#5
To reset the ECU on an 01, you only need to leave the negative terminal off for an hour or so.
Here's the relearn proceedure: Did nothing for me... I tried it at least 4 times.
What problems are you having? Also, did your CEL come back on?
Here's the relearn proceedure: Did nothing for me... I tried it at least 4 times.
DESCRIPTION:
“Idle Air Volume Learning” is an operation to learn the idle air volume
that keeps each engine within the specific range. It must be
performed under any of the following conditions:
--Each time IACV-AAC valve, throttle body or ECM is replaced.
--Idle speed or ignition timing is out of specification.
!!!!PRE-CONDITIONING MUST BE DONE 100%!!!!
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment.
--Battery voltage: More than 12.9V (At idle)
--Engine coolant temperature: 70 - 99°C (158 - 210°F)
--PNP switch: ON <~~~~~IN PARK
--Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light only small lamps.
--Cooling fan motor: Not operating
--Steering wheel: Neutral (Straight-ahead position)
--Vehicle speed: Stopped
--Transmission: Warmed-up
For A/T models withOUT CONSULT-II and M/T models, drive
vehicle for 10 minutes.
!!!!PRE-CONDITIONING MUST BE DONE 100%!!!!
OPERATION PROCEDURE WithOUT CONSULT-II
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING”
(previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.
ITEM SPECIFICATION
Idle speed M/T: 625±50 rpm
A/T: 700±50 rpm (in “P” or “N” position)
Ignition timing M/T: 15°±5° BTDC
A/T: 15°±5° BTDC (in “P” or “N” position)
NOTE:
If idle air volume learning cannot be performed successfully, proceed as follows:
1) Check that throttle valve is fully closed.
2) Check PCV valve operation.
3) Check that downstream of throttle valve is free from air leakage.
4) Adjust closed throttle position switch and reset memory.
(Refer to Basic Inspection, EC-111.)
5) When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the problem.
It is useful to perform “TROUBLE DIAGNOSIS — SPECIFICATION
VALUE”, EC-143.
6) If any of the following conditions occur after the engine
has started, eliminate the cause of the problem and perform
“Idle air volume learning” all over again:
--Engine stalls.
--Erroneous idle.
--Blown fuses related to the IACV-AAC valve system.
“Idle Air Volume Learning” is an operation to learn the idle air volume
that keeps each engine within the specific range. It must be
performed under any of the following conditions:
--Each time IACV-AAC valve, throttle body or ECM is replaced.
--Idle speed or ignition timing is out of specification.
!!!!PRE-CONDITIONING MUST BE DONE 100%!!!!
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment.
--Battery voltage: More than 12.9V (At idle)
--Engine coolant temperature: 70 - 99°C (158 - 210°F)
--PNP switch: ON <~~~~~IN PARK
--Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light only small lamps.
--Cooling fan motor: Not operating
--Steering wheel: Neutral (Straight-ahead position)
--Vehicle speed: Stopped
--Transmission: Warmed-up
For A/T models withOUT CONSULT-II and M/T models, drive
vehicle for 10 minutes.
!!!!PRE-CONDITIONING MUST BE DONE 100%!!!!
OPERATION PROCEDURE WithOUT CONSULT-II
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING”
(previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.
ITEM SPECIFICATION
Idle speed M/T: 625±50 rpm
A/T: 700±50 rpm (in “P” or “N” position)
Ignition timing M/T: 15°±5° BTDC
A/T: 15°±5° BTDC (in “P” or “N” position)
NOTE:
If idle air volume learning cannot be performed successfully, proceed as follows:
1) Check that throttle valve is fully closed.
2) Check PCV valve operation.
3) Check that downstream of throttle valve is free from air leakage.
4) Adjust closed throttle position switch and reset memory.
(Refer to Basic Inspection, EC-111.)
5) When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the problem.
It is useful to perform “TROUBLE DIAGNOSIS — SPECIFICATION
VALUE”, EC-143.
6) If any of the following conditions occur after the engine
has started, eliminate the cause of the problem and perform
“Idle air volume learning” all over again:
--Engine stalls.
--Erroneous idle.
--Blown fuses related to the IACV-AAC valve system.
11-14-2006, 08:01 PM
#6
Senior Member
Join Date: Aug 2000
Posts: 339
I got the "P0505" when I cleaned my IACV. Tried to troubleshoot every possible related component and nothing until finally I sent it to the dealer and it was a bad ECU. My car had high idle(~1,000 rpm) after cleaning the IACV. The ECU reset worked at first but as soon as you shut the engine off and turn it back on, it would go back to the high rpm.
I got mine replaced under emmssions warranty(8 yrs/80K). Good luck!!!
Forgot to mention I have a 2002 Maxima
I got mine replaced under emmssions warranty(8 yrs/80K). Good luck!!!
Forgot to mention I have a 2002 Maxima
11-14-2006, 10:11 PM
#7
I got mine replaced under emmssions warranty(8 yrs/80K). Good luck!!!
01-18-2007, 05:26 PM
#8
Newbie - Just Registered
Join Date: Jan 2007
Posts: 14
IACV Idle Air Control Valve - Fried ECU - BAD ECU
Have a look inside my ECU.
Motor on IACV siezed and fried ECU.
I have changed IAVC only to find out ECU is shot. If anyone has any leads on how I can get a ECU for a good deal please let me know.
Sheesh! What a ride this problem has been. $$$$$
2001 Nissan Maxima GLE w/traction control
Motor on IACV siezed and fried ECU.
I have changed IAVC only to find out ECU is shot. If anyone has any leads on how I can get a ECU for a good deal please let me know.
Sheesh! What a ride this problem has been. $$$$$
2001 Nissan Maxima GLE w/traction control
01-20-2007, 05:42 PM
#13
Senior Member
Join Date: Dec 2004
Posts: 331
Sorry to hear about your recent problems. You know I really believe it's just a matter of time before more people on the org start complaining about having ECU problems. At the time when my ECU went bad I could hardly find anyone on the org with a similar problem. I really think Nissan should do a recall on both the ECU's and MAF's.
01-20-2007, 06:01 PM
#14
Originally Posted by Redstone
Sorry to hear about your recent problems. You know I really believe it's just a matter of time before more people on the org start complaining about having ECU problems. At the time when my ECU went bad I could hardly find anyone on the org with a similar problem. I really think Nissan should do a recall on both the ECU's and MAF's.
01-20-2007, 07:06 PM
#15
Senior Member
Join Date: Dec 2004
Posts: 331
Originally Posted by monty31
Is there a place you can send complaints to Nissan? We should organize a list of everyone that has had this problem and then make a formal complaint.
I beleive the place that this type of complaint would normally be sent to is the Consumer Affairs Department for Nissan located in Gardena, CA. Their address should be in your warranty booklet. This is the same place I contacted by phone when my ECU went bad and the car was just about 82,000 miles which normally if it had been under 80,000 miles it would have been covered by the 80,000 mile Federal Emissions Warranty. Nissan gladly told me that have not had similar complaints with ECU on the 5.5 gen Maximas and no recalls are currently on the books for this problem. In addition they said the car is already over the 80,000 miles so I would have to fix it on my own which is what I did. Would I buy another Nissan? At this point maybe or maybe not.
01-21-2007, 11:59 AM
#16
Originally Posted by Redstone
I beleive the place that this type of complaint would normally be sent to is the Consumer Affairs Department for Nissan located in Gardena, CA. Their address should be in your warranty booklet. This is the same place I contacted by phone when my ECU went bad and the car was just about 82,000 miles which normally if it had been under 80,000 miles it would have been covered by the 80,000 mile Federal Emissions Warranty. Nissan gladly told me that have not had similar complaints with ECU on the 5.5 gen Maximas and no recalls are currently on the books for this problem. In addition they said the car is already over the 80,000 miles so I would have to fix it on my own which is what I did. Would I buy another Nissan? At this point maybe or maybe not.
02-06-2007, 05:10 PM
#20
Originally Posted by nicks79
what are the symptoms of bad ECU? high idle? I have a jumpy idle, drops to below 500 then back to normal each time.
weird
weird
02-07-2007, 11:27 AM
#21
the org...not what it was
iTrader: (8)
Join Date: May 2004
Location: Communist Wealth of Virginia
Posts: 8,143
Originally Posted by monty31
This thread is related to P0505 - IACV shorting out the ECU. If you don't have thatCEL, it's most likely an unrelated problem.
been having this problem for over a year now, even got a new DE-k cause my previous one threw a rod, and i'm still having the same problem with the fluctuating idle in 'N' & 'P' and 1100rpm when the car is in drive. I'm going to try and get a new ECU and hopefully that will resolve the issue.
02-07-2007, 06:51 PM
#23
Originally Posted by alicious
been having this problem for over a year now, even got a new DE-k cause my previous one threw a rod, and i'm still having the same problem with the fluctuating idle in 'N' & 'P' and 1100rpm when the car is in drive. I'm going to try and get a new ECU and hopefully that will resolve the issue.
02-08-2007, 07:34 AM
#24
the org...not what it was
iTrader: (8)
Join Date: May 2004
Location: Communist Wealth of Virginia
Posts: 8,143
Originally Posted by monty31
If I understand you...you have P0505 and have replaced the IACV with a new unit?
Now I have a new engine, IACV, same ECU and still have the problem
02-08-2007, 01:39 PM
#25
Originally Posted by alicious
you are correct, and it didn't work.
Now I have a new engine, IACV, same ECU and still have the problem
Now I have a new engine, IACV, same ECU and still have the problem
02-08-2007, 07:44 PM
#26
the org...not what it was
iTrader: (8)
Join Date: May 2004
Location: Communist Wealth of Virginia
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Originally Posted by monty31
Time to shop on car-parts.com for a used ECU. Yay!!!
02-08-2007, 10:01 PM
#27
Originally Posted by alicious
When you swamped your ECU did your key still work in your ignition? I had heard that once you swap out your ecu that it wouldn't work with a new one or something like that...
02-19-2007, 03:25 PM
#28
Newbie - Just Registered
Join Date: Feb 2007
Posts: 1
Originally Posted by fornimage
I got the "P0505" when I cleaned my IACV. Tried to troubleshoot every possible related component and nothing until finally I sent it to the dealer and it was a bad ECU. My car had high idle(~1,000 rpm) after cleaning the IACV. The ECU reset worked at first but as soon as you shut the engine off and turn it back on, it would go back to the high rpm.
I got mine replaced under emmssions warranty(8 yrs/80K). Good luck!!!
Forgot to mention I have a 2002 Maxima
I got mine replaced under emmssions warranty(8 yrs/80K). Good luck!!!
Forgot to mention I have a 2002 Maxima
I'm having the same symptoms with my 01 Maxima. The dealer has replaced the IACV and has told me the ECU needs to be replaced too. I asked them if it would be covered under the 8yr/80K warranty and he said 'no' because the failure was caused by the IACV (which is not a warrantied item)...seems like a bunch of B/S to me! I only have 74K on my car so, regardless of why the ECU failed, this should be covered under the warranty, right?
Did anyone else have problems getting the dealer to cover the ECU under warranty with a failed IACV with code P0505??
I've called Customer Affairs to see if they can help me 'convince' the dealer.
02-19-2007, 04:02 PM
#29
Senior Member
Join Date: Aug 2006
Posts: 601
Originally Posted by Redstone
Sorry to hear about your recent problems. You know I really believe it's just a matter of time before more people on the org start complaining about having ECU problems. At the time when my ECU went bad I could hardly find anyone on the org with a similar problem. I really think Nissan should do a recall on both the ECU's and MAF's.
You can only find out that you have a bad ECU if you replace the certain sensor and check wiring. If everything checks ok we suspect ECM so we go to parts and they have spare ones just for testing. So if you go to a competent dealer and let them perform the diag you might save yourself some $$. Many ppl just throw parts at it and then they come in. Ends up costing more.
BTW another thing that shorts ECMs in our cars is electronicly controlled engine mounts. Seen 3-4 so far. 6 speeds neet to not worry as they are only liquid filled.
03-25-2007, 11:23 AM
#30
Newbie - Just Registered
Join Date: Mar 2007
Posts: 1
IACV and ECU
I am battling the Nissan dealership in MA now with this problem. The ECU in my 2001 Maxima shorted out. The cause was a "seized IACV". Nissan is saying it is not under the 8/80 warranty because the IACV caused the failure. But if the car was running fine and they fail at the same time, how do I know I need to fix the IACV?
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
03-26-2007, 11:40 AM
#31
the org...not what it was
iTrader: (8)
Join Date: May 2004
Location: Communist Wealth of Virginia
Posts: 8,143
Originally Posted by Danp
I am battling the Nissan dealership in MA now with this problem. The ECU in my 2001 Maxima shorted out. The cause was a "seized IACV". Nissan is saying it is not under the 8/80 warranty because the IACV caused the failure. But if the car was running fine and they fail at the same time, how do I know I need to fix the IACV?
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
if your extended warranty is bumper to bumper and included all electrical compenets then there should be no problem. I'm not sure how yours is set up but mine will cover whatever i need whenever i need it all i have to do is take it to a shop and it's a wrap.
05-29-2007, 02:04 PM
#32
Newbie - Just Registered
Join Date: May 2007
Posts: 1
Same problem here....
Originally Posted by Danp
I am battling the Nissan dealership in MA now with this problem. The ECU in my 2001 Maxima shorted out. The cause was a "seized IACV". Nissan is saying it is not under the 8/80 warranty because the IACV caused the failure. But if the car was running fine and they fail at the same time, how do I know I need to fix the IACV?
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
My extended warranty won't kick in, because they are saying Nissan should pay.
Can anyone provide advice?
Sorry if I am missing answers on other posts... this is my first time here.
THANK YOU!!
I guess poor electronic design does not constitute a recall. The fact that the a "shorted" IACV can destroy the ECU is simply poor electrical engineering on the part of Nissan. I'll sell the car after I fix it. A problem like this is typically referred to as a "hand grenade in the basement" - and until Nissan modifies their design, I cannot trust the reliability of the car. It "smoked" while I was running an errand, and I had to pay to have the car towed to the dealer, and then to my home after they quoted me $1300-$2000 to fix it!
05-29-2007, 10:17 PM
#33
Senior Member
Join Date: Dec 2004
Posts: 331
I am wandering if the damge shown in the pictures below could be the result of a shorted IACV. A code of P0650 came up. The damage part shown in these pics look similar to the part in the picture in post #8 except that org member has a 2001 GLE with traction control and the ECU shown below came from a 2003 Auto without traction control.
http://i187.photobucket.com/albums/x...k/DSCN0145.jpg
http://i187.photobucket.com/albums/x...k/DSCN0150.jpg
http://i187.photobucket.com/albums/x...k/DSCN0152.jpg
http://i187.photobucket.com/albums/x...k/DSCN0145.jpg
http://i187.photobucket.com/albums/x...k/DSCN0150.jpg
http://i187.photobucket.com/albums/x...k/DSCN0152.jpg
05-30-2007, 03:49 PM
#34
Member
Join Date: Oct 2006
Posts: 30
Thank god i found this thread.
My 2001 maxima recently stopped idling while on highway and then it burned something. initially it wasn't giving any CEL. and then finally it threw the P0505.
I suspect my ecu is fried. can you guys tell me how to locate and unhook the ecu.
also can somebody tell me where to get cheap IACV-AAC valve.
My 2001 maxima recently stopped idling while on highway and then it burned something. initially it wasn't giving any CEL. and then finally it threw the P0505.
I suspect my ecu is fried. can you guys tell me how to locate and unhook the ecu.
also can somebody tell me where to get cheap IACV-AAC valve.
06-01-2007, 02:08 AM
#35
Originally Posted by choopster
Thank god i found this thread.
My 2001 maxima recently stopped idling while on highway and then it burned something. initially it wasn't giving any CEL. and then finally it threw the P0505.
I suspect my ecu is fried. can you guys tell me how to locate and unhook the ecu.
also can somebody tell me where to get cheap IACV-AAC valve.
My 2001 maxima recently stopped idling while on highway and then it burned something. initially it wasn't giving any CEL. and then finally it threw the P0505.
I suspect my ecu is fried. can you guys tell me how to locate and unhook the ecu.
also can somebody tell me where to get cheap IACV-AAC valve.
06-01-2007, 10:39 PM
#37
Member
Join Date: Aug 2006
Posts: 34
I'm SOL...problems just after 80K miles!
Has anyone ever tried reprogramming their keys to work with a replaced ECM without going to a dealer/mechanic? (I found a Nissan procedure but have not tried it yet) I'll try digging for it again in case anyone wants see it.
Has anyone ever tried reprogramming their keys to work with a replaced ECM without going to a dealer/mechanic? (I found a Nissan procedure but have not tried it yet) I'll try digging for it again in case anyone wants see it.
06-06-2007, 01:47 PM
#40
I'm a new member and I'm glad I found this post. I just bought a 2000 maxima SE on saturday the 2nd. It is auto with traction control and every other option. It just rolled over to 97,000 miles. When I bought the car, the SES light was on and I was thinking it was a co2 sensor. Just today, on my way to work, the idle jumped up to around 1400 and stayed there. Now..... I'm fearing the worst. I will be going to Autozone to get a code reading. This is my first Maxima and I'm pretty dissapointed. Is it safe for me to not replace the IACV and just replace the ECM or should I play it safe and replace both if that's the problem? (Which I'm almost 100% convinced it is)
