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-   -   No start, code U1000 ABS controller area network line malfunction. (https://x.nissanhelp.com/forums/altima/30253-no-start-code-u1000-abs-controller-area-network-line-malfunction.html)

M-train 01-01-2018 09:49 AM

No start, code U1000 ABS controller area network line malfunction.
 
05 Altima SER auto, 195k miles.
New oem IPDM [about a year old]
New oem injectors
New oem MAF
New oem crank/cam sensors
New oem coil packs.

Also checked for compression, and everything is fine there as well with 225psi. each cyl [new engine, running good for about a year now, built by me].

Checked all fuses, and grounds. I was getting a generic U1000 with a PO726 [bad crank sensor] so I changed out the crank sensor, and still no start. Battery at 12.7v.

I hooked up a volt meter to the crank sensor red/green power wire, and instead of getting 12v with the key on, I'm getting 9.3v.

I checked the ECM relay on the IPDM as per the wiring diagram, and I'm getting 12v on two of the four relay sockets in the IPDM, and 9.3v on one socket.

Here is the Crank sensor wiring diagram. I should be getting 12v with key on, right out of the IPDM red/green wire, but I"m not, only 9.3v.
http://i.imgur.com/WvY2gaL.jpg

smj999smj 01-01-2018 11:25 AM

I'm assuming you are checking for voltage at the red/green wire with the sensor unplugged. So, unplug the harness connectors at the ECM and IPDM/ER. Run a jumper from the positive battery to the appropriate R/G wire at the IPDM/ER and see if you get battery voltage at the R/G wire at the sensor and the appropriate R/G wires at the ECM harness connector. A better check would be rather than supply voltage to the circuit, use an ohmmeter to check for excessive resistance between the connectors at those R/G wires and to also make sure there is no continuity to ground. If those are good, I would check locate your ECM grounds and clean them up and make sure they are tight as well as the one for the crank sensor. Then, plug everything back in and see how it goes.
There was a TSB for U1000/U1001 codes if I remember correctly for a number of models in the mid-2000's. It involved cleaning all of the ground connections and gave diagrams to where those connections are. You may want to check the "knowledge base" section for the TSB.

M-train 01-01-2018 11:58 AM

One of the first things I did was check the grounds, sand, and add some dielectric grease.

I will try the jumper wire, and see what happens.

M-train 01-01-2018 01:20 PM

Ok, I used a jumper wire from the battery to the E122 connector, pin 33 [r/g wire] that was connected to the IPDM fuse box.

Now I showed 12v at both the crank sensor connector, and ECU pins 109, and 111, which is the correct voltage for this points.

M-train 01-01-2018 02:35 PM

1 Attachment(s)
The problem is [outside of it being in the low 20's today with the wind blowing] that 9.3 frigging volts at the ECM relay. Let me see if I can get another wiring diagram to load.

https://x.nissanhelp.com/forums/atta...1&d=1516596066

Take a look at pin number 35. That pin "should" be 12v from the Key on to activate the relay, but its not, its ZERO volts with the key on. None of those pins in that connector have any voltage when the key is on.

There has to be a wire that powers the ecm relay, and that source/wire should be where the 9.3v are originating. I think its pin number 35 which is a red wire, but again it check out a zero with the key on [pin plugged in]

M-train 01-01-2018 05:36 PM

Since I'm not getting voltage a pin 35 with the key on, do you think the key switch is bad?

Surely its not a bad ECM as it wouldn't keep the key from supplying 12v in the "on" position given everything else in the car works [ie headlights, windows, blower motor, cooling fans, etc?

M-train 01-01-2018 06:55 PM

One other thing.

I've read where when the ECM goes bad you WON'T SEE THE CEL when you turn the key to ON.

I no longer see the check engine light, cel, when the key is ON. Plus I my scanner won't communicate with the ecm unless its in the enhanced mode.

M-train 01-02-2018 02:25 PM

I really hate it when I'm reading about a problem like mine, and its never updated.

Here is something I just read, and I think it might be my issue because I had the u1000, and 726 code.

Quote:"On the maxima's with the 5 speed automatic the code p0726, even though it appears on the scanner as a transmission code, it is actually a communication issue. The ecm communicates with the tcm via 2 CAN communication lines. The CAN lines transfer large volumes of data between many modules throughout the vehicle, these data lines are a new solution to help decrease the number of wires between modules by compiling relevant information for each module. If you have the code p0726 look for an accompanying U1000 code, if present diagnose the U code first.

On 5 speed automatics test both (yellow and blue) CAN lines for continuity between ecm and tcm, again look for no resistance, 0.00 ohms, if no resistance for check for short to ground, if no short to ground or circuit breaks inspect connectors. If ok suspect tcm."
:Quote.

smj999smj 01-02-2018 07:00 PM

It's hard for me to read your diagrams; even if I copy them and expand them, the resolution is so poor that it's hard to make out, but I think I can tell what is what. Plug the IPDM back in and leave the ECM unplugged as well as the crank sensor. Then check the voltage; I have a feeling you will see battery voltage. I'm thinking you are losing your voltage through the ECM, which may or may not be an issue.
First things first: P0726 is not a faulty crank sensor code, especially combined with a U1000 CAN communication error code. If you had a crank sensor malfunction code with those codes (I think it's P0335, if I'm not mistaken), then I could see the reason of replacing the crank position sensor. Since you don't, it is more likely a communication problem between the ECM and TCM, which could be a CAN communication wire between the two modules or a bad module.
I would perform the diagnostic steps for the P0726 and see what you come up with. Diagnosing U-codes is a real pain and you have to check all of the various control units for codes and go by a chart in the FSM to figure out what the circuit is that is affected.
My gut feeling is that you have a bad ECM, but there's no way to confirm that 100% without doing some more diagnostic work.

M-train 01-04-2018 01:25 PM

Your right its a bad ECM.

I went on another forum, and the guy helping there suspected the ECU, and I used Justanswer [which I've used before with good results], and the tech there diagnosed it as being a bad ECM.

I was getting 9.8v at all of the sensors. This might have been a bad ignition switch, but there was voltage at the ECM when the key was on so that rules that out.

Since the SER has its own part number for the ECM the tech at JA said I should just send mine out for a repair [as finding a used ecm might be a looong wait].

Problem is I called the company the tech recommended, but they said they didn't have the parts to repair that ecm, so I'm kinda wondering if that is going to be a problem with every company.

smj999smj 01-04-2018 07:01 PM

Circuit Board Medics is the one I usually recommend.

M-train 01-05-2018 01:02 PM

Quote:

Originally Posted by smj999smj (Post 103535)
Circuit Board Medics is the one I usually recommend.

I actually found you recommending them on a net search.

This is going to be a problem, I think. Circuit Board Medics said they can't fix it, same with NPC Automotive Computers can't fix it [both top names], plus another I contacted on Ebay.

So, I'm wondering what it is about the Altima SE-R ECU that has these top companies either not wanting to touch it, or not having parts?

Question, since the SER is a relatively rare car [heard production number from 5k total to 7k which is still kinda low], why does the ecm have to match EXACTLY, as it will still need to be re-flashed at the dealership?

I mean, if you get a ECU for an SER from another Altima of the same year, with the same engine/transmission, and options, with basically the only electronic difference being the programming of the SER to make it have the whopping 10hp more than an Altima SE with the same engine, why couldn't that ECM be used?

smj999smj 01-08-2018 06:30 AM

I would think that they'd be the same with the exception of the software programming, but I can't tell you for sure. Have you tried searching for a used one on Car-part.com?

M-train 01-09-2018 05:32 PM

Quote:

Originally Posted by smj999smj (Post 103567)
I would think that they'd be the same with the exception of the software programming, but I can't tell you for sure. Have you tried searching for a used one on Car-part.com?

Yes, that is actually where I found one, and it should be here by either tomorrow, or Thursday.

Hopefully, I won't get screwed by the dealership when I take the car in to have the ECU reprogrammed. My car isn't exactly stock anymore so I'm sure they are going to try to hit me for repairs for some of the "deleted" parts [ie egr, intake manifold block off plate, customized intake, etc.

I hope they [the dealership] can just stow the BS, and do what I need them to do.

M-train 01-09-2018 05:38 PM

I'm kinda distrustful about ecu repair companies.

I called/emailed several of these repair companies, and ALL of them said the same thing, "we don't have the parts to fix your particular ecu".

Their replies got my spider sense tingling. What I'm thinking is these places are just taking the circuit board out of another ecu with the same part number, and swapping into the case/box of the ecu you send them, then shipping it back to you as "repaired".

Another thing these places can do is to heat up your ecu board with a heat gun, and get the solder soft, and making contact again. Don't laugh, I've "fixed" several graphics cards from my home computer over the years by "cooking" them in the oven for a bout 10 minutes@400 degs.


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