Earlier I posted on the General Forum about my leaking heater core, and its subsequent replacement at a trusted shop. Dash reassembled and core replaced, the car now idles poorly, will not accelerate, and the check engine light is on. The diagnostic computer could not communicate with the ECM, but could communicate with the "safety" computers (SRS, ABS...). Since the ECM was directly under the leaking heater core, a Nissan mechanic friend of the shop owner said the ECM should be removed, allowed to dry, and then reinstalled. Does this sound like a reasonable solution, or should I plan on buying a used ECM? As always, thanks for your assistance.

 

It is possible that your Engine Control Module sustained water damage. However, before doing anything to the ECM, I would spend an hour or two on straightforward diagnostic work. That's because the ECM is often wrongly blamed for problems with the sensors or wiring.

You will find instructions to do a DTC readout and reset the Check Engine light at:
http://vbxmaxima.8m.com/ecu.html This procedure requires only a screwdriver. Post the codes here and we can proceed with that new information.

When you have accessed the ECM to do the DTC readout, feel around in that area. If the carpet is wet, perhaps the ECM did get wet. If the carpet is dry, perhaps this problem is independent of the heater core leakage.

 

I am going to the shop tomorrow with the printed instructions you have provided. I will keep you updated, and as always, I appreciate the response. Thanks.

 

I picked up the ECU and the inside is gunked with congealed coolant. There even appears to be a plastic coating which has formes an "arc" between each standing lead. When the ECU is installed, the check engine light remains solidly on, and no diagnostic can be run. I have already called around for prices on a new ECU, $600 was the best from Dave Burnette at South Point, and a used one runs $225. Thanks for any follow up.

 

Idea #1) Try to clean your ECU. At this point you have nothing to lose. Put two gallons of clean water in a bucket, add six ounces of rubbing alcohol. Drop your dirty ECU in the bucket, soak it for two minutes, and pull it out. Give it a day or two to dry, install it in your car, and hope for the best.

Idea #2) I have heard that some Auto Recyclers sell used ECUs for $75 each, guaranteed. I have never bought one, so cannot confirm this story.

Idea #3) Buy a remanufactured ECU directly from the vendor. They will charge more than $75 but might buy your core. Call 1-888-326-8646 and 1-877-687-3267. I'm not endorsing these outfits as I have no experience with them. I found their numbers in the small ads in the back pages of automotive magazines.

 

I had a bad experience with the remanufactured ECU thing. I had a Galant GSR 5 speed, of which about 1500 were made. The ECU went bad and I couldn't start the car. I had to find a remanufactured ECU because Mitsubishi wanted 1300 for a new one. I got one from the remanufacturer and it worked for about two months, then decided that it wanted to shut down 2 of the 4 cylinders. I then had to replace the computer again, this time taking it to Mitsubishi. They took it apart and I found out that they had used a Eclipse GS ECU in the box and forced it to fit. I then went back to the original place and they told me that they could no longer accept it for return although it had a 2 year warranty because I had opened the case. Be VERY careful if you decide to get a refurbished one.

 

Are you sure you want to thank him? Hehe!
http://216.122.219.59/forums/showthr...threadid=25661

J/K Daniel. I know you try to help everyone.

Instead of dunking the whole ecu(somehow that doesn't sound right) I would just use an alcohol dipped q-tip and carefully clean each male and female connector on the ecu and ecu main harness connector.

 

Turbolaw99 said "the inside is gunked with congealed coolant." Cleaning only the connectors on the ECU is just scratching the surface of the problem.

 

Then wouldn't be better to disassemble the ecu housing and clean it by hand? If the casing is easily taken apart that is. I have not heard about dunking the whole ecu into a bucket of water before. Covered in the FSM?

 

Yes, it would be better to disassemble and clean by hand.

This question was not followed by three smilies, so I'll take it at face value. The FSM contains very little information about repairing anything. The general philosophy of the FSM is the same as the dealer's service department. Quickly identify the failing component and replace it with a new Nissan part. They have no interest in rejuvenating a failed component by cleaning or lubricating or resoldering. They favor the fix which is fastest and most profitable.

 

I don't quite know how to take the smilies comment. Care to elaborate? Sorry.

Well I agree and disagree w/ you Daniel. I don't have any experience w/ the 4-gen NISSAN FSM at all. But one case in point is the 3-gen VTC assemblies. My NISSAN FSM is very detailed on how to take apart and inspect this piece. I think if Nissan really wanted to screw us owners(even more than usual), they could have left this info out and just recommended just replacing this part(Nissan cost is $400+ each. Each head has one)

But on the other hand your are right in the fact the Nissan FSMs are not nearly as detailed as they once were. I have a Nissan FSM for a early Datsun(maxima 810 or 240z). In that one they even detail how to disassemble the alternators and how to clean each little part. Same for the early type relays!

I have to say in general though, Nissan FSMs are pretty detailed in the repair aspects. IMHO it's the typical Nissan mechanic/Nissan dealership that has the crappy "replace until the problem is gone" mentality. The fsm does cover how to get to the root of the problem, but the typical dealership doesn't spend the time to go through all the steps in the FSM beucase just how you say, it's alot easier and profitable just to replace all the suspect parts.

What do you usually use for repair references? The Nissan FSM or the Haynes/Cliltons?

 

I thought you might be joking about whether the FSM suggested dunking the Engine Control Module. It doesn't tell anything about repairing it. Nor does it tell anything about repairing the Transmission Control Unit or any of the five Local Control Units on late-model Maximas. The FSM wants the technician to treat these major electronic components as "black boxes". Their philosophy is "Don't fix it, just replace it."

The home mechanic might have the motivation to do this. The professional has an incentive to fix it fast and move on to the next job.

I have all three books and find them all useful. The FSM has far more detail than the aftermarket repair manuals. Chilton and Haynes have lots of useful photos. Of the two, I prefer Haynes. For a detailed comparison of the three books go to http://vbxmaxima.8m.com/manualcompare.html

 

Well Daniel, there's not much that can be done to electrical components, other than just cleaning them. Repairs to these components are WAY beyond the ave or above ave DIYer unless they are an electrical expert.

You stated the fsm has no information about repairing ANYTHING. So I thought you meant EVERYTHING. Maybe you just meant the major electrical components??

I think you just repeated my statement about the mechanic's use of the fsm and their general attitude about repairs so I assume you agree.

 

You are right for electronic components but not electrical components. FSM doesn't tell much about electrical items which can be repaired. This forum is replete with complaints about Maxima starter motors. I believe many of these starters need only cleaning and lubrication of the shifter lever and pinion assembly. FSM doesn't tell how to do this. Some starters need only a new set of brushes and a commutator clean-up. FSM doesn't suggest this. Haynes tells how to replace the solenoid on an otherwise healthy starter; FSM doesn't.

No, it goes beyond that. Many Maxima owners have questions and complaints about engine idle speed. This is controlled by the Idle Air Control Valve - Auxiliary Air Control valve. In my experience this part can sometimes be rejuvenated by nothing more than disassembly, cleaning, and reassembly. FSM won't tell you that.

We agree. You, I, and some other Maxima.Org members are interested in fixing their own cars. The man who does his own repairs
- saves money
- learns more about how his car works
- takes pride in his mechanical skill and self-reliance

One reason I participate in this forum is to encourage other owners to tackle at least some of their own repair work. The more you do, the more you can do. After a while you find yourself thinking "The dealer charges $XXX for that?!?"

 

After reviewing the friendly debate, I cleaned the ECU. Took it completely apart, cleaned carefully w/alcohol, employing the Q-Tip method, and voila. I will have to wait until Monday to take the ECU to the shop.

I had nothing to lose with this attempt and I appreciate all of the feedback. I hope it works, but I am prepared to pay for the replacement. Ah, there is nothing like the satisfaction of a job well done, even more so if it actually works.

 

We had some electronics that were flood damaged.

Some people tried plugging them in, and immedietly
killed them... The water and gunk shorted them
out and nuked the electronics.

I thoroughly washed a bunch of them out with with water... and let them dry COMPLETELY before plugging them in. (I used a hair dryer, plus let them sit for a couple days) Most of these recovered just fine!

Hopefully, the damage was not already done....

Good Luck!

 

What is the differentiation in serial numbers located on the ECU. I am sure ones for manual differ from auto transmissions, but there is no federal or Cali differentiation, is there? Thanks.

 

I have no information on Engine Control Module serial numbers. Perhaps your Nissan dealer can help with that.

There are apparently some distinctions between California and non-California models. Look at the vehicle identification plate riveted to the engine compartment firewall on the passenger side of the vehicle. Immediately below the Vehicle Identification Number is the Model Variation information, beginning with BLHUL. The penultimate character in that line is:
N = Canada
V = California
U = US, not California