Friday 29 May 2015

Inifiniti G35 2003 :: Wet IPDM issue, how to fix it

Introduction to the wet IPDM issue

The Infiniti G35 is a technology filed car. as early as 2003 it already had a CAN bus and a few computers that take advantage of this network. This complexity comes with the cost of horrible situations when a failure of the CAN bus occurs. the problem described below affects the G35 after heavy rain fall. the I.ntelligent P.ower D.elivery M.odule cannot do it's job properly at that time and it affects the whole CAN bus. so all communication between the other computers in the car is not working. This kind of issue is really annoying on a luxury car and can lead to a loss of confidence in the car itself if not fixed.This situation occurred to me after a heavy rain, a quick search on the web revealed a few Youtube videos showing the trouble but no clear solution or understanding, people are stating that the trouble goes away by itself after a while. That is no answer for me, hopefully all those hours spent on understanding the G35 wiring diagram before buying the car was worth it!


*The video is not mine btw

the list of symptoms were noticed on a single drive home lasting about 35 minutes and totaling 50 km. the list is quite exhaustive and so was the situation. not the kind of crappy behavior you would expect from a luxury car.... 


  • Engine ECU works fine
  • Radio works fine
  • ABS works fine
  • Sunroof works fine
  • door lock works fine
  • SRS seems fine
  • interior car lighting
  • the only thing in the dashboard that works is the fuel level gauge, alternator warning light, ABS system is OK


All other gauges are not moving or being totally erratic.
  • Tachometer
  •  Speedometer
  •  Engine temperature
  • Check engine light flickers
  • VDC light is on all the time
  • SLIP light on all the time
  • CAN bus communication is down or erratic across all systems,  
Additionally those systems are not working properly.
  • -all systems relying on the CAN bus are in fail safe mode, some shut themselves down, some try to cope with the situation
  • -dashboard clock stops working
  • -VDC and traction control are OFF
  • -Transmission ECU is in fail safe mode since the CAN bus is down, gear shifting is extremely harsh at all engine loads,
  • -gear shifting is relative to car speed only
  • -transmission will never down shift no matter how hard you step on the accelerator
  • -manual gear shift mode is not working,
  • -while cruising on the highway the transmission down shifts hard for no reasons on constant engine loads.
  • -headlights are jumping from low to hi beam (people are thinking you want to tell them something ). you cannot engage hi beam yourself, it's like being epileptic.
  • -electric radiator fan control, this one I can't confirm but it is sufficient to say this is quite critical as this is controlled by the IPDM and if the fans don't work when they should, you would get an overheating engine due to a bad CAN bus... what a lovely feature!!



Battery compartment without battery , IPDM and fuse box plastic cover
On older cars a 'gutter box' of some sort was draining the rain water coming to the bottom of the windshield and conveniently channeled it to the bottom of the car, it is called a cowl dash.on conventional design, only the wiper arms mechanism and wiper motor are installed there, end of the story. Nissan on the G35 decided they wanted to save weight and probably some money so they designed the car WITHOUT a cowl dash. Result:: when it rains, or you wash your beloved car, there is a waterfall running on the firewall inside the battery and Brake booster compartment. at the bottom of those boxes are holes meant to drain those boxes.

You can notice dirt marks around the top wiring harness, it indicates water flows there often then around the IPDM, this is a rust hazard to consider too..

First problem: the IPDM sits low cramped in the battery compartment adjacent to the firewall, there is always a humidity risk for this device since the water flow is in it's back, common sense suggest to never place critical electrical components in the way of water ...this is only common sense though...

IPDM with it's plastic cover, fender side fuse box out of the way
Second problem: the battery compartment is only equipped with one drain hole at the bottom and IT COMPLETELY CLOGS WITH THE YEARS! this lead to water accumulation in the bottom of your battery compartment, with sufficient water input it can get high enough to disturb your IPDM and voila You reproduced the problem on your otherwise pristine G35! (mine was completely clogged with mud and the water level was about 1/2" high.) looking down the battery compartment does not show much, you need to bend out of the way stuff and go there with your fingers to tell.

unclogged drain shown,IPDM out of the way, the drain is visible now

Third problem - the plastic battery tray gets filled with water under the battery and there is no drain holes in it.
( the blame goes to the cowl dash less design ) so you carry around about a glass or two of water that splashes here and there on hard accel/braking/cornering. Removing the battery tray and drilling holes at the bottom would drain that water accumulation when it fills.
The battery tray gets filled with stagnant water as the years are passing...

Fixing it 

tools needed to fix this

  •  shop towels.
  •  small air compressor equipped with a duster.
  • something to unbolt 10 and 12mm nuts. (for baterry removal)
  • narrow flat screw drivers can be useful to release the IPDM from it's bracket.

 things to do ( 15 to 30minutes )

  1. Remove battery compartment plastic cover.
  2. Remove the plastic part that meets with the lower part of the windshield.
  3. take out your battery.
  4. take out the water from the battery tray.
  5. slide up the IPDM and fender fuse box, let the IPDM rest on the battery tray.
  6. unplug the drain using fingers or better.
  7. dry out as much as possible remaining droplets in the whole battery compartment with a towel.
  8. reinstall IPDM and fuse boxes on their brackets.
  9. remove IPDM and fuse boxes plastic covers.
  10. using the duster generously dry all the wires connectors at the base of the IPDM. catch the escaping water with a towel using the other hand.
  11. do the same thing in the fuse boxe.
  12. do the same thing in the wiring harness behind battery tray and coming from under it.
  13. install plastic covers on IPDM and fuses boxes.
  14. Reinstall battery.
  15. Start the car to confirm the problem went away.
  16. Stop car, reinstall the lower windshield plastic cover.
  17. Install battery compartment plastic cover.
  18. Enjoy life.


The IPDM is placed at what seems to me THE WORST PLACE EVER for a module as critical as it is.This module controls electrical power distribution across various systems and by placing it there endanger the CAN bus operation. I hope NISSAN was wise enough to improve on their electrical designs over the years...


  1. Thank you so much for this detailed, well written post. I had the exact same problem and was able to fix it - something my auto electrician wasn't able to do ! (I found it easier to get to the drain by taking out the battery tray btw).

  2. Awesome thanks for the write up man, Did this to my car today, The little rubber plug around the drain hole fell out though, Is that a big deal?, The Infiniti dealer in Halifax apparently sprays the IPDM with Rust Check Red to keep moisture away from it, I did that too

    1. the grommet in the hole serves to protect things passing through the hole from being cut from vibration. I think it's OK on that side of the car. thanks for the comment!

  3. Cool man no problem!, Yeah it fell inside the car somewhere when I was fumbling under the IPDM trying to find the whole which was clogged with mud, I was thinking being a bit bigger might help it drain better too, Little worried the wires might get damaged

  4. Nice write up! I have an 03 Coupe with non functional headlights and turn signals. I bought it that way thinking it couldnt be too hard to Ive determined that no power is getting to the lights but the fuses are good. Nothing on that cluster switch does anything.. no ding, no signal of anykind on dash or turn sinals , headlights.Im wondering if the ipdm has been wet. i see some signs of water/rust in that area. I was trying to remove the ipdm for inspection and cleaning and easily separated all of the terminal ends except for the last one and im having trouble getting it out. any suggestions? the other terminal ends had obvious releases but the last one has none.any help would be appreciated. BTW, the car runs great, brake lights and hazzards work.

    1. I have no suggestion about how to pull it out, but yeah trying another IPDM can be useful.


  5. I have an 2003 infinity i35 and my tcs off light is on and abs light is on and my speed and tach is not working at all and it idles good but bogs down and has major loss of power and even at idle while pushing throttle all the way it it will start to big way down as well I have u1001 code and p1212 code and p0300 dtc code

  6. I have the same problem electrician installed a new ipdm and car still won't start

  7. While doing this I accidentally pulled the wires from the white and grey clip that is on the end of them that plugs into the box can anyone please tell me the order they go in from top to bottom so I can put them back in and start my car I have been trying to figure this out for months now and am desperate for help

    1. last summer I pulled a whole CAN bus wiring off a 2005 sedan G35. I added pictures from the connections into the IPDM to the end of the blog post. I can take more if need be.

  8. This comment has been removed by a blog administrator.

  9. My AT CHECK light came on after a mechanic fooled around & touched my ipdm box is there anyway to figure what could cause the light to clme on in the first place

  10. Thanks for the very detailed procedure. Solved my issue like it was nothing.

    1. I was so stunned the day I found the culprit I could not let it go undocumented, it's my pleasure!

  11. I’m having the issue of both my headlights no turning on. My vds amd slip dash lights are in as well. Tried fuses and relays for headlights and they are all good. No moisture in the ipdm box or battery area. Can’t figure out. And ideas?

    1. VDC/SLIP bulbs lit mean the VDC system is not working at all. probably allows to spin as much as you like and does not have abs at the moment.
      VDC and ABS fuse need to be OK. the IPDM might be internally damaged since only some systems are impacted, if you can try a replacement one that may do the job.

  12. Did everything to IPDM still does not start

    1. symptoms on mine did not affect the engine operation much. every other systems. the ( engine ECU + key transponder ) communicate directly. you may have EFI issues brewing.

    2. Let me know if you fix it. I'm having the same issue

  13. Wow that was very helpful,thanks.

  14. Hi, would this cause me to loose all electrical power to the car?

  15. Thank you ever so much for this outstanding post. I own a 2003 G35 sedan. Having the exact problem you describe, the Infiniti dealer informed me that water in the electronics was the culprit but did nothing to remediate the problem. After experiencing these electrical failures many times after rain storms, I am addressing the problem myself. Your explanation of what is happening is greatly appreciated. Thank you!!!

  16. I have a 03 g35 sedan doesnt crank or start I changed the starter three ignition switch. Checked relays and still nothing gets it started could the ipdm be my problem as well??

    1. Did the same u did and not car wont start or crank stuck at this point changed ipdm and bow i have no lower to starter hear fuel pump turn on someone help plz

  17. Yeah hi my name is Matthew Ruby I have a 2003 Infiniti G35 I replace the brain that's underneath the sea now my seat don't go back and it won't start what's that problem

  18. Hi everyone, the car was sold last autumn IPDM still working well, I have nothing more to do about infinitis and can't help much further on this topic.

  19. I have a 2003 g35 reader wnt read codes it wnt communicate any ideas

  20. Ok so you noted all the problems...but you didn't say anything on how to fix it..wasntbhelpfull at all ..

    1. Hi, mine just needed to be dried out and drain to be unplugged. there was no permanent damage done on mine. some do. good luck!

  21. Hey does anyone on here know if a 03 sedan AUTO ipdm with the wiring would work on a 03 coupe MT

  22. I have the same problem. Beer the ipdm now car won't start. What's the solution???

  23. Sorry, not beer. Typo. Water.

  24. I fixed the problem. It was the fuel pump. I did change the fuel pump however, just swapped out the pump. I bought the assembly which fixed the issue.

  25. Yo this saved my ass. All I had to do was cleaned out the green nasty buildup on the cable ends of the connectors with brake cleaner and a air can duster. After cleaning make sure to reset the car with a OBD2 scanner, should start right up.