No com on IPDM

I have some tough diagnostic that i have been dealing with at the shop. I got nissan 2005 altima 2.5lts SL. Came in for wiper goes on, headlights on and cooling fan on when key is in on or run position. Car starts and runs. I have communication in any other modules but the IpDM which is simply underhood intellegent fuse box. There are power and ground on this module. I checked the can lines and they are both messy when i back probe at the data link connector(high and low lines are messy and not mirroring each other.) I have some pics to attach if i can. When can lines are unplugged from IPDM, com signals gets cleaner and they mirror each other. I thought i found my problem but when i back probed on the IPDM can lines (connector plug in) signals get messy again and i once again uplugged it and found the my can signals voltages are low(high line is .22v at the peak and -22v at the valley) and my can low signal voltage is below specs of 1.5v to 2.5. Now my question is why is it i’m not getting a cleaner signals at IPDM connector unplugged, instead i’m getting a very low voltage? I thought first that i might have partially short to ground in the circuit but the rest of the modules can lines are cleaner when IPDM is unplugged, so i find myself hard to believe that i have short to ground issue guys. I need ur thoughts about this. And by the way i printed the can diagram and the can high and low are all tied up to every single module in the vehicle. Isn’t it will pull the voltage down when one can line is short to ground and u will not see any of that cleaner signal from any other modules? I appreciate ur comment here guys. Thanks

I could not find my cleaner signals waveform pics when IPDM is unplugged, u guys gonna need to trust me on that. I’m thinking i have a bad IPDM but i don’t like my can lines signal voltage when can lines connector is unplugged, it is really low. By the way the terminating resistor when i did my research live in IPDM and ECM. Specs says 120ohms but i’m reading 128ohms and i don’t know if it is an issue. Thanks

if your reading 128 ohms which is pretty close to 120 ohms. that is saying one of the resistors is junk in the network.you should see 60 ohms roughly on pins 6 and 14 of the can network. simplething you can do is keep checking the resistanceof the networkunplug the ecm then it should read open. that tells you the resistor in the pcmis fine and the one in the ipdm is junk.

Ok i got that but i still cannot understand why am i not getting cleaner signal when back prove the can lines connector of IPDM unplugged, but i can get cleaner signals and voltages within specs at either data link connector or BCM network.

is this the only module that the can lines look like that? either way you should see 60ohms. you can always try running redundant com wires to the ipdm. but i think you have a bad ipdm. verify powers/grounds at the module and call it.

So far i’ve checked BCM and at the data link connector. Hard to get to the rest of the modules in th car but i will try checking ECM (plug and unplug) and see what it looks cleaner.

I’ll let you guys know what happens by monday. I appreciate ur time guys. Thank You

if i were working on this andi had good powers/grounds and 120 ohms across pins 6 &14 instead of 60 then unplugging the pcm seeing infinite after that.id feel comfortable putting an ipdm in. let us know what happens this week. good luck

I will. Thanks i appreciate it

Finally i found someone with similar fault as mine. I have been having this problem for the past 2-3 years on my infiniti fx35 2005 model without finding the fix. I have the same fault as you do. When the ignition is turned ON position; the front wiper is stuck off and doesn't turn on with the switch, but back wiper works as it should. No current is going to the AC compressor, headlights and fog lights don't work with the switch, the fans are stuck on HI speed, the night light on the front cig port is stuck on. When i plug in a scanner it sees and connects to all other modules in the car, except the IPDM, which it doesn't see on the car. Please friend, have you been able to resolve this problem as i believe we share same faults.

Please bro i beg u, can you post your resolution on that issue, im still having the same problem with my infiniti fx35

I also suspect the IPDM having a short inside, but i don't wanna replace it without being sure if that is the problem. Please reply me Blessie@123

have you solved this issue having the same trouble .

From the looks of the thread it turned out to be the ipdm. In your case you need to test the can network with car off battery disconnected and ohm test pins 6 and 14 of dlc connector like what has been said above