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Discussion Starter · #1 ·
hello i could really use some help 2008 nissan frontier 4.0 will not crank with key all dash lights come on. has codes u1000 u1001 .i checked all fuses checked ok ,tried a different ipdm no change swapped efi relay and starter relay no change.if i pull the starter relay and power probe the lower connection the starter cranks fine so tells me starter and wiring from relay are ok.but for some reason no power to starter with the key please help thank you
 

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u1000 and u1001 are communication errors,nothing is going to work until the network works. there are several possibilities, shorted or open network, bad module on network bringing it down, or bad power/ground to one of the modules and more...
 

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Check the five fusible links located in the plastic case directly behind the (+) battery post to make sure all those links are not "blown" and are still intact. Use the voltage & continuity tester functions on a digital multimeter to test them.

Also, try running a ground wire directly from the (-) post of the battery directly to the engine block. If the truck starts after you run a ground wire from the (-) battery post to the engine block, then you have a short within the (-) ground cable coming off the battery. If your Frontier is exposed to road salts, then you might want to check ALL your ground points.

Hope this helps.....
 

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Discussion Starter · #4 ·
ok will check fusible links and ground tomorrow thank you.i read something about trans module causes this they said unplug pass side of trans and try to start .did that still no crank.
 

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Discussion Starter · #5 ·
how would i check the modules.i work alot on bmws and i have test loops for bypass/testing for can bus signals. this nissan has no can bus loop slots .my obd2 scanner shows no can bus status or how many modules.so how would i go about finding what can bus modules it has and to test those modules for communication .thank you
 

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how would i check the modules.i work alot on bmws and i have test loops for bypass/testing for can bus signals. this nissan has no can bus loop slots .my obd2 scanner shows no can bus status or how many modules.so how would i go about finding what can bus modules it has and to test those modules for communication .thank you
you will need the schematics for your car, and it would be best to have a scan tool that can communicate to all modules, to see what is and isnt talking. lastly you will most likely need an oscilloscope to check the can bus signals on the can bus/busses on the truck

schematics are here - once the site is back up


just as a possible issue have you checked your radiator fluid for smod its possible that fried the tcm control module and thus the no start.

 

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Was the truck working fine previously? Those codes usually set when you have a bad/lose battery terminal, wire or ground.
 

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Discussion Starter · #8 ·
first off thank you for your help.the truck was towed to me from a friend he said will not crank .so i checked fuses and connections and grounds and tsb"s all check ok.today i checked fusible link box on the positive battery post checks ok power on both sides of the fuse links.i checked for 12v power to ipdm on the red wire circut #48 key on check ok.but i get no signal to starter relay. circut #19 white wire of ipdm box if i apply power starter cranks and vehicle starts.so i decided to crawl under disconnect tcm plug to see if that makes it start.i found the trans plug already disconnected so i plugged back in vehicle still will not crank with the key and with key on headlights come on and cooling fan runs never did that before and it will not start hot wireing circut #19.so i disconnected trans plug and if i apply power to starter relay lower connection #19 it will crank and start only with transmission unplugged.so i know something must be wrong with the TCM.but i cannot get the vehicle to crank with the key and thats all im trying to get it to do.my friend brought me a used ipdm cause thats what i thought it was but there was no change still no crank with key.and i attached a ground from neg battery post to engine block still no change.any help would be greatly appreciated thank you
 

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Discussion Starter · #9 ·
radiator coolant looks ok see no milk.i do assume tcm has issues since i found it unplugged.everything shows the vehicle still cranking over with the key if tcm is unplugged .i just need to get it to crank over with the key
 

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power at 48 ipdm means you are ok for park neutral switch. relay coil+
19 is out to starter
3 is power from ignition switch when turn to crank -->becomes 19 if relay closes
relay coil ground is from ipdm cpu which is on can bus

ipdm cpu goes into fail safe if its not talking to bcm and ecm - not sure if also needs tcm

here is the same failure mode in a nissan no crank, fans running and can bus errors...
different cause, but it shows how the ipdm will not engage the starter relay without the correct communications on the can bus

 

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Discussion Starter · #11 ·
so ignition has signal to ipdm .i believe its the tcm causing my issue.i used a better scanner today and will not communicate with any modules if trans tcm is plugged in as soon i unplug tcm scanner talks to ecm,abs,srs with no tcm comms still will not crank with key.circut #9 from tcm has no 12v with key on.i applied 12v with powerprobe still wont crank with the key.so only thing i can come up with is a bad tcm causing no crank with key they want 800 for a used tcm or 1200 for a complete trans.my friend i dont think wants to fix due to cost of repair. such a poor design i have never had a vehicle no crank condition you could not confirm .im guessing its the tcm from all the pin tests and diagnostics but no way to confirm 100%.and could only verify by spending 800+ hoping it works.i better make sure to stay away and never recommend a nissan in the future.i wish there was a way to confirm the no crank condition 100% .thank you for all the input and help if he decides to put a trans in it i will keep you posted on if it fixed it.
 

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did you ever download the manuals i referenced above, the starting system manual and the network manual both seem to state you do not need the tcm can connection for start

i noticed you did not mention talking to the bcm with your scan tool - BCM is a must to start
"BCM sends a starter request signal to the CPU of the IPDM over the CAN communication" STR-9

per the starting manual STR-9
"TCM supplies power to the starter relay inside the IPDM E/R when the selector lever is shifted to the P or N position."
STR-8 also has a good block diagram on the starting system


per the network manual LAN-7,8
"if can comm to tcm is disconnected ipdm operation is normal"

so i think yes the tcm is crashing the can bus when connected, but your no start issue is a 2nd issue most likely BCM based on what your scan tool sees or rather dosen't see.

i would test all the bcm functions to see if anything works or is it dead...
 

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Discussion Starter · #13 ·
yes i looked at the manuals same as what i have with prodemand thank you.when the tcm is unplugged i have communication with ecm,abs,bcm,srs no tcm.if i plug tcm in i have no communication with any modules.all of the tests for the ipdm checks out exept to starter relay that is the only thing with the ipdm that is not in spec.i have no input 12v signal to starter relay wich wiring diagram shows coming from #9 circut of tcm what is confusing is when i power up circut 9 of tcm i still have no crank condition from key.i will double check bcm with scanner thank you.you say the manual says does not need tcm to crank all of the videos i recently seen on nissan no crank condition they say is due to failed tcm wich apparently is really common and causes no crank condition with nissans that tells me you need tcm to crank.i was hoping to power circut 9 verify it cranks with the key then sell the tcm.without being able to verify i just hope thats the cure.i will let you know what i find thank you
 

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well, when I say you don't need tcm can connection that's strictly for the ipdm and its functions. still may need can working, see below...

i know tcm can bus connection tells the meter/M&A(instrument cluster) the shift positions selected including park/neutral

the instrument cluster pin 7 then feeds a signal via pin 102 of ECM that the trans is in p/n.
this signal is 0v when in p/n, battery voltage in any other position. (this may be your smoking gun of not starting and needs to be 0v along with the tcm#9 12v). you can see this in the ecm data monitor--> p/n posi sw

in the ecm there is also a start signal on/off and ignition switch on/off data monitors

in bcm there is a data monitor ign on sw in the immobilizer section.

so check your data monitors in ecm/bcm/ipdm/meter for any clues

try feeding 12 volt to the ipdm at (pin48/tcm pin9) and 0v to the ecm pin 102. see if that gives you the ability to start, if not then that tcm being smoked is killing something else to prevent start.

good luck at this point i would need to actually be hands-on to get further in the diag.

report back any findings and maybe that will give a new plan of attack.

edit - forgot to mention and i know its easy to overlook is the transmission actually in either park or neutral?
 

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Discussion Starter · #15 ·
i will look over all data monitors.tcm pin 9 i have fed 12v there was no change.I will check ecm pin 102 for 0 voltage that i have not checked yet.on my scanner neutral safety switch is showing correct gears when i shift through the gears.thank you i will let you know what i find
 
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