2013 versa won't start after changing radiator fan - Page 2 - Nissan Versa Forums
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post #11 of 24 Old 07-08-2017, 05:55 AM Thread Starter
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It was able to erase the TCM codes cuz I scanned it again right after and no codes came up but after a few try's of starting the car the the codes came back.
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post #12 of 24 Old 07-08-2017, 02:17 PM
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The codes are stored in the TCM and are sent to the ECM after you clear it. You can try to take out the TCM connector and short power and ground pins to try to clear it. I don't have diagrams for your car so I can't tell you what those pins are but it's probably best to just use thr right scanner.
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post #13 of 24 Old 07-08-2017, 05:07 PM
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I note we still have no admission from OP the TCM was even touched, so why are we talking it? Yes, I know, the codes, but WHERE did they come from??? They did not just magically appear. There IS a reason for that. Need to hear what it was.

I'm having trouble with the TCM being self 'internal' powered too, flash memory to hold software in place yes, but self powered......................I doubt it. A battery disconnect powers it down too.

And, the LAST THING you want to do is start 'shorting out' pins, that is DEATH with any electronic module on the planet where I come from, a sure mark of incompetence.

The codes come back because the issue still likely EXISTS.

Last edited by amc49; 07-08-2017 at 05:18 PM.
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post #14 of 24 Old 07-08-2017, 05:48 PM
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Went and dug up a TCM schematic from NICOclub and it clearly shows battery or key-on power supplying the power to TCM in at least 4 places. No self power anywhere in it I can see. The codes are either for shorted or disconnected TCM connectors. I would be looking closely at the connectors and if they are plugged in fully but I would be disconnecting the battery before I did so.

REALLY should have disconnected that battery before the work; that is often death not doing so working on modern cars.

Last edited by amc49; 07-08-2017 at 05:50 PM.
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post #15 of 24 Old 07-08-2017, 07:17 PM
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Quote:
Originally Posted by amc49 View Post
I note we still have no admission from OP the TCM was even touched, so why are we talking it? Yes, I know, the codes, but WHERE did they come from??? They did not just magically appear. There IS a reason for that. Need to hear what it was.

I'm having trouble with the TCM being self 'internal' powered too, flash memory to hold software in place yes, but self powered......................I doubt it. A battery disconnect powers it down too.

And, the LAST THING you want to do is start 'shorting out' pins, that is DEATH with any electronic module on the planet where I come from, a sure mark of incompetence.

The codes come back because the issue still likely EXISTS.
You've never heard of an ECM with capacitors? That will hold it's memory for a long time even with the battery disconnected.
Go re-read what I said. The TCM has no power or ground with the connector disconnected. Shorting out pins will only discharge the capacitors.

OP, thinking about it, try disconnecting your battery cables and short them together. I don't know whether or not it will work, but try it.
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post #16 of 24 Old 07-09-2017, 02:20 PM
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There is no such thing as an ECM WITHOUT caps. That is NOT what holds memory or software in a piece of solid state now, it's flashable memory or commonly rewritable EEPROMs (electrically eraseable programmable read only memory). Any more than the basic instruction build on that NON-volatile software that a flash chip carries (needs no power to keep the information) like fuel trims or LEARNED shift strategies or other transient operating learning is in volatile RAM and it fails and erases as soon as the battery is disconnected and intended to do so, it's how you get back to a clean slate of operating instructions to start building it all over.

Shorting caps out to power them down is fine if the individual cap lead can be found by itself to do so but pins coming off a board are commonly hooked to 500 other parts in a system string and you are asking for it assuming you can short that 'cap' pin as it will flow power that in some cases can damage the parts in the string and behind the short that are NOT caps. The only way one could ever do that would be by very exact instruction to do so and that will be pretty rare.

When you wipe codes the controlling ECM (or maybe TCM, the duties are often divvied up) will run the pertinent self tests and past a certain number of fault finding queries and key-ons figure in there often, the codes will pop back up if the hard fault still exists, that is what tells you you haven't fixed the issue. The fact they disappeared for a little bit most likely means you DID get them erased.

I build computers among other self taught things.

No insult intended at all and I apologize if it seems that way but I do know a thing or two. Not much about Nissan per se (learning very fast though) but enough to know they do much of what the rest on the manufacturing world does. So far and looking in Nissan service manuals I see nothing I already do not know or would not guess after 20+ years on Ford electronic systems.

Last edited by amc49; 07-09-2017 at 02:52 PM.
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post #17 of 24 Old 07-10-2017, 07:38 PM
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I can tell you that trans codes will get stored in th TCM and clearing the ECM won't clear them. These cars have separate modules unlike, say ford Eec and many others which have a common PCM.
If the TCM codes aren't cleared, they will get set to the ECM every time after clearing the ECM codes, although not all TCM codes will show in the ECM.
I can also tell you that on a 2009 Versa 1.8 CVT, disconnecting the battery will not clear TCM codes.
I can also tell you that certain TCM codes will keep the car from starting, we had a 2010 Versa CVT and it had u1000 and p1777 codes IIRC. Towed in no start, cleared the TCM codes and it started right up.
My assumption is that while disconnecting the battery or harness connectors it tripped TCM codes which are preventing the car from starting, that is why I suggested he clear the TCM codes before chasing a non existing problem.

The suggestion he try shorting pins to clear it was just a suggestion he could try without a scanner that may or may not work and while the TCM is disconnected from power and ground. I would personally just find a scanner.

I have no doubt that you know what you're talking about, but I have first hand experience with these cars and have been specializing in electrical and diagnostics for a while now.
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post #18 of 24 Old 07-12-2017, 05:41 AM
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You completely ignore the fact that if the hard fault is STILL PRESENT no code clearing on the planet will fix it. When I spoke of ECMs divviying up duties I meant just like computers do say main bios control, the main computer looks around for other add-on modules and then 'yields the floor to them' to do their separate thing and if they list a code then it relays to the ECM as well. Of course the TCM can prevent starting, what if owner tries to start in gear? Trans range switch likely reports to TCM. May not be able to clear lower level codes like TCM without using Nissan Consult to do it.

My overall point was to try to drag the OP into admitting he did more than said to affect the outcome, but it appears he has flown the coop. The danger there was him doing the work with no battery disconnection and he said so. Gonna feel real silly if car towed only to find out the TCM simply was not fully plugged in all the way. What the codes implied. Why I keep saying too the hard fault may still be present. Still not plugged in right. Maybe fried now too.

We make things as easy or as hard on ourselves as we can it seems.

Again, no insult intended at all, I just tend to go all the way. My bad.
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post #19 of 24 Old 07-12-2017, 05:51 AM
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I wasn't ignoring the codes, I was saying that the TCM sends certain trans codes to the ECM, which trips the SES light. The TCM stores it's own codes separately. When clearing the ECM codes, the TCM is not cleared, so it sends those codes back the the ECM again and again until the TCM codes are cleared. I've seen this on many different cars, including the Versa.
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post #20 of 24 Old 07-13-2017, 02:23 AM
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Just went and ran each one of the codes presented there as far as TCM functions and pretty much all involve disconnection of main power from the battery to various parts inside TCM, so doublecheck the connector. After that it can be wire shorts to ground but all four unlikely. There is a battery and key-on fuse at 10 amp each that need to be good, they supply power to the module. I could not find ANYTHING saying the codes had to be reset to start the car (in fact part of the diagnosis process for each WAS starting the car) but one of the fuses (key-on one) also powers the trans range switch and the inputs go into module and that one would most definitely affect starting I'd bet.

Maybe the codes still being present stop all that but I couldn't find anything saying that anywhere in the dtc wiping instructions. From 2014 Versa service manual which seems to be the same as the '13.

(EDIT) I found more. The TCM DOES transmit the dtc to the ECM and the code also STAYS in the TCM............................................... BUT........................this following line from the service manual, I copied it verbatim.

'NOTE:
• If the battery terminal is disconnected, the TCM memory is erased. The disconnection time varies from several
seconds to several hours.'

Last edited by amc49; 07-13-2017 at 02:59 AM.
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