Do you have any codes? What are the symptoms? Have you tried cleaning the ECU connectors?

 

No I clear all codes but I remember message was "LOST COMMUNICATION WITH GENERATOR". I cleaned all pins and removed ECU and put it back.

I have problem with ECU for a while. On my way back from vocation may car stop and dealer reprogram unit to allow me to back home (600 km). (They need 4 days and $1500 to put new one) . So they told me that this option will allow me to drive but every time I shut off engine I have to disconnect battery to allow ECU to reboot and it working for two month already but of course it is annoying.
In meantime I try to get new unit which is very difficult.

 

I would suggest first taking the wiring connector off of the alternator and cleaning it really well. They are known to get oil dripping on them. There is a splash shield you may be able to find to install on the alternator to help in the future

 

You need to get the code and then diagnose it according to the factory service manual. The CRDs are not well documented in the FSM so you may need to get an online subscription or pay a garage to print out the diagnostic procedure.
There is only 1 wire going to the alternator for control of the field. You could start at the alternator end of the wire and check it out.

 

thank you.

 

Can you give me address of those subscriptions forum to get wire diagram.

 

I have not used this website so you may want to research it before paying up:
https://www.techauthority.com/en-us/products/?category=1

Any independent garage will have a subscription account. I think this video gives a taste of some of the diagnostics you can do with a real scanner.

 

Wojtek90, did you recently replace the alternator with an aftermarket unit? I did, and immediately ran into alternator/ECM communications issues resulting in good charging only after the first 1, 2, 3,4 starts after battery-disconnection. It seems random how many I get. Others on JF with the 3.0l CRD OM642 diesel engine have observed similar behaviour after reman or aftermarket alternator installs.

The single-wire to ECU is a digital "LIN-bus" protocol wire. I dug deep enough to find chip-level regulator information and there are multiple variants of the LIN-Bus protocol and that may be the source of these issues. I still have a sticky U1132 bad-comms fault, but think I need to address it by getting the right regulator on the back of a "guaranteed to fit" alternator.

I checked the continuity of my "field wire" (actually LIN-Bus), which was good, and have the following notes left in my cellphone:
"PCM Connector C2 Pin 19 is the field wire, BR/DG (brown/dark-green) C104 Cable K125 to C104 pin 12, then C102 pin 2" Whatever that means :frown2: I think that was a trace from ECU to alternator.

I will see if I can find the wiring diagrams from which I was working at the time.

Meanwhile, anyone reading this thread know where I can get an alternator splash guard?

 

Wojtek90, did you recently replace the alternator with an aftermarket unit? I did, and immediately ran into alternator/ECM communications issues resulting in good charging only after the first 1, 2, 3,4 starts after battery-disconnection. It seems random how many I get. Others on JF with the 3.0l CRD OM642 diesel engine have observed similar behaviour after reman or aftermarket alternator installs.

The single-wire to ECU is a digital "LIN-bus" protocol wire. I dug deep enough to find chip-level regulator information and there are multiple variants of the LIN-Bus protocol and that may be the source of these issues. I still have a sticky U1132 bad-comms fault, but think I need to address it by getting the right regulator on the back of a "guaranteed to fit" alternator.

I checked the continuity of my "field wire" (actually LIN-Bus), which was good, and have the following notes left in my cellphone:
"PCM Connector C2 Pin 19 is the field wire, BR/DG (brown/dark-green) C104 Cable K125 to C104 pin 12, then C102 pin 2" Whatever that means :frown2: I think that was a trace from ECU to alternator.

I will see if I can find the wiring diagrams from which I was working at the time.

Meanwhile, anyone reading this thread know where I can get an alternator splash guard?

I know this is an OLD thread, but I am having nearly the exact same issue! Having a lot of trouble finding others with this issue, but this one sounds really similar! My story:

Battery light came on while driving. Every day driver, no issues until this. Voltage was draining, ended up having to get a tow home. Replaced alternator (PIA). Seemed fine for about 20 miles, then light came back on. Battery was not charging (tested voltage while running at battery terminals, LOW voltage, like 7). Thought maybe bad alternator from parts store (reman), so bought another (new), replaced AGAIN. Seemed ok, then battery light came back on after about 65 miles. Unhooking the field generator wire (single small wire that runs to "regulator" on alternator) and plugging it back in seemed to work. I got really good at getting to that wire, and drove it like this for a couple weeks, every 30-100 miles having to unhook and re-connect that wire every time the battery light came on. I installed a voltage meter next to the steering column so I could monitor voltage from inside while driving (they neglected to include a gauge on the dash, grr), so was able to verify that indeed, the battery was not getting voltage from the alternator when the battery light came on. All signs pointed to bad ECM/PCM, so I shelled out about $900 USD for the ONLY one I could find in North America. Seller assures it's good. They flashed it to my VIN, and a few days later, it arrives. I go to swap it out. Now I have the red lightning bolt of death, several codes that didn't exist before, and the Jeep now won't start AT ALL. Swapping the new back for the old PCM changes nothing. Gave up. Left sitting for a bit, battery was totally dead. Two days on trickle charger, and battery (1.5 years old) now won't hold a charge. Replaced with new battery, reading 12.7V, and still same issues. No start. I can't locate any loose, corroded or shorted wiring, though trying to trace all these lines from the harness is what led me to this post. I have searched hi and lo for ANY info on this topic over the last couple months, and this is the only post that seems to replicate what I have going on. Sorry for the novel, but REALLY hoping I can figure this out! It was driving fine, other than the battery no charge issue, and now it won't start at all, but nothing changed other than unplugging and plugging in a new PCM. All connectors look clean and straight, so I have no idea what the issue is...

 

PIn locations on ECM C2

 

Looks like my notes were from the following diagram, but note that this is from the generic manual, not *necessarily* applying to the CRD variant.

 

ECM C1 connector:

 

Jeep Grand Cherokee WK 3.0l OM642 CRD diesel ECM/PCM pinouts (2008, should apply to 2007)
Please note this puts the lie to my cell-phone notes about pin 19 on C2. See pin 88 on C1 marked "LIN Bus", and the colour is shown as White/Blue.

Jeep Grand Cherokee 3.0l OM642 CRD turbo-diesel ECM pinouts (2008, should also apply to 2007?)
Connector C1 Pinout
Pin Circuit Description
1 K11 16BL FUEL INJECTOR NO. 1 HIGH-SIDE CONTROL
2 K12 16BL/VT FUEL INJECTOR NO. 2 HIGH-SIDE CONTROL
3 K13 16BL/RD FUEL INJECTOR NO. 3 HIGH-SIDE CONTROL
4 N/C N/C
5 N/C N/C
6 K902 20GY/WT O2 1/1 PUMP CELL CURRENT TRIM
7 K844 20RD/VT CAMSHAFT POSITION SENSOR 5 VOLT SUPPLY
8 K900 20BR/RD SENSOR GROUND
9 K934 20OR EXHAUST GAS PRESSURE SENSOR GROUND
10 K944 20BR/DG CAMSHAFT POSITION SENSOR GROUND
11 K312 18GY/OR EGR AIRFLOW CONTROL VALVE POSITION SENSOR SIGNAL
12 N116 18BR/VT CRANKCASE VENT HEATER CONTROL
13 N/C N/C
14 N/C N/C
15 K853 20RD/VT CRANKSHAFT POSITION SENSOR 5 VOLT SUPPLY
16 N/C N/C
17 N/C N/C
18 F858 20GY/YL EXHAUST GAS PRESSURE SENSOR 5 VOLT SUPPLY
19 K356 20RD/BK BOOST PRESSURE SENSOR 5 VOLT SUPPLY
20 N117 20GY INTAKE SWIRL SERVO MOTOR CONTROL
21 N/C N/C
22 X635 20GY/DG BOOST PRESSURE SERVO MOTOR CONTROL
23 K369 18RD/GY FUEL PRESSURE SOLENOID 12 VOLT SUPPLY
24 K315 18GY/PK EGR AIRFLOW CONTROL VALVE MOTOR (-)
25 K14 16BL/YL FUEL INJECTOR NO. 4 HIGH-SIDE CONTROL
26 K38 16BL/DG FUEL INJECTOR NO. 5 HIGH-SIDE CONTROL
27 K58 16BL/WT FUEL INJECTOR NO. 6 HIGH-SIDE CONTROL
28 K960 18BR/VT INTAKE AIR TEMPERATURE SENSOR GROUND
29 N/C N/C
30 N/C N/C
31 K41 20DG/BK O2 1/1 REFERENCE SIGNAL
32 N/C N/C
33 K44 20YL/GY CAMSHAFT POSITION SENSOR SIGNAL
34 N/C N/C
35 G123 18PK/RD WATER IN FUEL SENSOR SIGNAL
36 K923 18GY/DG WATER IN FUEL SENSOR GROUND
37 K957 18BR MASS AIR FLOW SENSOR GROUND
38 N/C N/C
39 G224 20YL/GY OIL TEMPERATURE SENSOR SIGNAL
40 F851 20DG OIL PRESSURE SENSOR 5 VOLT SUPPLY
41 K313 18DG/GY EGR AIRFLOW CONTROL VALVE SUPPLY
42 K668 20BR/BK INLET AIR PRESSURE SENSOR 5 VOLT SUPPLY
43 K350 20RD/WT FUEL PRESSURE SENSOR 5 VOLT SUPPLY
44 N/C N/C
45 N/C N/C
46 N/C N/C
47 K366 18BK/BL FUEL QUANTITY SOLENOID 12 VOLT SUPPLY
48 K99 16GY/BR O2 1/1 HEATER CONTROL
49 K638 16BK/DG FUEL INJECTOR NO. 5 LOW-SIDE CONTROL
50 K611 16BK/BL FUEL INJECTOR NO. 1 LOW-SIDE CONTROL
51 K658 16BK/WT FUEL INJECTOR NO. 6 LOW-SIDE CONTROL
52 K222 18BR/RD ENGINE COOLANT TEMPERATURE SENSOR GROUND
53 Z753 16BR/BK CRANKSHAFT POSITION SENSOR SIGNAL NO. 2
54 N/C N/C
55 N/C N/C
56 K914 20BL/DG FUEL TEMPERATURE SENSOR GROUND
57 Z43 20DG/BL O2 1/1 NEGATIVE CURRENT CONTROL
58 N/C N/C
59 N/C N/C
60 K2 20DG/RD ENGINE COOLANT TEMPERATURE SENSOR SIGNAL
61 K156 20BL/RD FUEL TEMPERATURE SENSOR SIGNAL
62 K916 20BR/WT PRE-CATALYST EXHAUST GAS TEMPERATURE GROUND
63 K915 20BR/WT POST-CATALYST EXHAUST GAS TEMPERATURE GROUND
64 K359 20GY/BR FUEL PRESSURE SENSOR GROUND
65 K181 20DG/VT FUEL PRESSURE SENSOR SIGNAL
66 K157 20BL/YL MASS AIR FLOW SENSOR SIGNAL
67 K390 20DG/PK EGR AIRFLOW CONTROL VALVE RETURN
68 N/C N/C
69 N/C N/C
70 N/C N/C
71 K34 20GY/YL EGR SOLENOID CONTROL
72 K314 18GY/RD EGR AIRFLOW CONTROL VALVE MOTOR (+)
73 K612 16BK/VT FUEL INJECTOR NO. 2 LOW-SIDE CONTROL
74 K613 16BK/RD FUEL INJECTOR NO. 3 LOW-SIDE CONTROL
75 K614 16BK/YL FUEL INJECTOR NO. 4 LOW-SIDE CONTROL
76 Z36 18YL/DG OIL TEMPERATURE SENSOR GROUND
77 K24 16DG/WT CRANKSHAFT POSITION SENSOR SIGNAL NO. 1
78 K936 20GY/PK OIL PRESSURE SENSOR GROUND
79 N/C N/C
80 K43 20GY/RD O2 1/1 POSITIVE CURRENT CONTROL
81 K35 20GY/BK EXHAUST GAS PRESSURE SENSOR SIGNAL
82 K37 20GY/YL BOOST PRESSURE SENSOR SIGNAL
83 K352 20YL PRE-CATALYST EXHAUST GAS TEMPERATURE SIGNAL
84 K21 20DG/WT INTAKE AIR TEMPERATURE SENSOR SIGNAL
85 K68 20RD/BL INLET AIR PRESSURE SENSOR SIGNAL
86 N/C N/C
87 K656 20BR/GY BOOST PRESSURE SENSOR GROUND
88 D509 20WT/BL LIN BUS
89 K353 20YL/WT POST-CATALYST EXHAUST GAS TEMPERATURE SIGNAL
90 K362 20DG/YL MASS AIR FLOW TEMPERATURE SENSOR SIGNAL
91 N/C N/C
92 N/C N/C
93 K370 18BK/WT FUEL PRESSURE SOLENOID CONTROL
94 K365 18YL/BK FUEL QUANTITY SOLENOID CONTROL
95 N/C N/C
96 N/C N/C

Connector C2 Pinout
Pin Circuit Description
1 K542 14BR FUSED ASD RELAY OUTPUT
2 Z816 14BK GROUND
3 A15 14RD/TN FUSED ASD RELAY OUTPUT
4 Z130 14BK/BR GROUND
5 F42 14DG/LG FUSED ASD RELAY OUTPUT
6 Z130 14BK/BR GROUND
7 K167 18BR/YL APPS NO. 1 SENSOR GROUND
8 N/C N/C
9 N/C N/C
10 N/C N/C
11 K355 20BR/DG EXHAUST DIFFERENTIAL PRESSURE SENSOR SIGNAL
12 K29 20WT/BR APPS NO. 2 SIGNAL
13 N/C N/C
14 G6 20VT/GY OIL PRESSURE SENSOR SIGNAL
15 F855 20PK/YL 5 VOLT SUPPLY
16 K354 20BR/LG EXHAUST DIFFERENTIAL PRESSURE SENSOR 5 VOLT SUPPLY
17 F856 20YL/PK 5 VOLT SUPPLY
18 N/C N/C
19 N/C N/C
20 N/C N/C
21 N/C N/C
22 V71 20VT/OR S/C SWITCH SENSE 1
23 N/C N/C
24 K23 20BR/WT APPS NO. 1 SIGNAL
25 N/C N/C
26 V72 20OR/VT S/C SWITCH SENSE 2
27 N/C N/C
28 V937 20VT/BR S/C SWITCH RETURN
29 N/C N/C
30 K951 20BK/DB EXHAUST DIFFERENTIAL PRESSURE SENSOR GROUND
31 N/C N/C
32 K31 20BR FUEL PUMP RELAY CONTROL
33 N/C N/C
34 N/C N/C
35 B15 20DG/WT BRAKE SWITCH NO. 1 SIGNAL
36 B16 20LB/DG BRAKE SWITCH NO. 2 SIGNAL
37 N/C N/C
38 N/C N/C
39 N/C N/C
40 K400 20BR/VT APPS NO. 2 SENSOR GROUND
41 F942 20PK/LG FUSED IGNITION SWITCH OUTPUT (RUN-START)
42 K343 20BR/YL FUSED ASD RELAY OUTPUT
43 N/C N/C
44 T752 20DG/OR ENGINE STARTER MOTOR RELAY CONTROL
45 N/C N/C
46 N/C N/C
47 N/C N/C
48 F26 20PK/OR IGNITION SWITCH OUTPUT (START)
49 N/C N/C
50 N/C N/C
51 D65 20WT/LG CAN C BUS (+)
52 D64 20WT/LB CAN C BUS (-)
53 N/C N/C
54 C13 20LB/OR A/C CLUTCH RELAY CONTROL
55 K363 20OR/BR PTC NO. 3 RELAY CONTROL
56 N/C N/C
57 N/C N/C
58 N/C N/C

 

That should be added to the diesel sticky

 

The alternator was put by dealership (I was on vacation trip 600 km from my home) and I wasn't able to drive.
So I let dealership to replace alternator ( $1400) and they told me that ECM unit need to be replace, but in order to let me go home they reprogramed it with "one start" option only.
I mounted battery switch and I am driving my Jeep since (3 month)disconnecting battery every time I shut engine off, till I will find the chipper way to replace ECM unit (now is about $1400).

 

Just to confirm the pin 88 info above is correct for the CRD and the wiring diagrams in the FSM are wrong for the CRD, the LIN wire is white with a blue trace

20210109_163216 by Old_Chad, on Flickr