JHFIII

Hey guys, On our trucks (01 specifically), how does a chassis ground return to the battery.? Lets I add a set of aux lights, or anything really, and I ground the piece to the frame or body. I know there are the two battery to body grounds on the drivers battery, and one (if I remember right) on the passenger battery. Are there larger ones from block to the body or frame somewhere? The reason I am asking is I am curious if you add something that has a little bit higher of an amperage draw (grounded to the frame) if there is enough ground going only through those body to battery (smallish) ground wires. Thanks John

Thanks for the reply Haggar, The testing referred to are Mopar1973Man's diagnostics I have done most of the FSM type stuff. I am going to run through it again this evening and see what I come up with. I know this is something that staring me right in the face, and Im just not seeing it.

Should that reading be taken with ignition on or off? I read the #5 step as meaning that I should have exactly 100 ohms, but sounds like I'm mixed up on that. Does ECM sending 8volts through the brown/white, ignition on sound correct? (measure with the ecm harness connected, igntition on) I have to check my notes, but I believe I measured the g100 gnd connector (disconnected) to relay 85 and got .1ohm. My confusion is that the wires all appear to show continuity, but something gives. For the record, I did clean g100 thoroughly. Once I got a surface rust and crud off , it actually looked pretty secure and clean.

Update to say that I got it running. The VP44 did indeed need to be replaced. With the relay bypassed it was only pumping lift pump pressure out of one injector line. The old one couldnt even be turned by hand, something definitely bound up in there. A little dab of yellow paint on the new vp44 key was definitely a big help to get it lined up right. Very happy to have it running. I still havent resolved my p0215 code, and I can only start it with the relay bypassed, but at least it roars once again. All signs say is has to be the brown white between the PDC and ECM. These are the results of the p0215 diagnostic: 1)Fuel pump relay 85(gd) to batt voltage =12v 2)Relay is good 75ohm 3)ECM 30/49 to batt voltage=12v 4)ECM 36 to relay 86 .2ohm 5)Relay 86 to G100 ground = 65ohm Im only getting about 8V from the ecm to relay 86, with the igntion hot. The brown /white from end to end reads .1ohm. The brown/white to ground does not register a reading on the multimeter. Im not sure what that means. Ive been hesitant to tap the brown white at the ecm and then the pdc connector and run an overlay wire to see if that fixes it, until I was absolutely certain (which Im still not, but I have a hard time blaming the ECM since its doing nothing else to make me think its on the fritz). Does anyone know if its possible to fish a new wire through the ECM loom? Or am I just better off running it on the outside. The last thing Id want to do is screw up other wires in the loom. Thanks guys

Finally got to the G100 ground. Nearly totally corroded. I'll be doing some wiring tonight and then I'll retest things with the voltmeter. Edit: Actually not as bad as I thought at first once the dremel wire wheel got done with it. Nice and shiny now, though.

It was outdoors. The ignition switch makes sense to me. It was a little musty in the cab. It wouldn't crank at all. Everything else electrical works fine. The only two things are the ECM sending low voltage through the brown white wire to the fuel pump relay, and the vp (which I suspect was on its way out when I parked it).

Hey guys, I think I may have finally found the culprit. With the ignition ON the ECM is only sending 7 volts to the brown/white, measured between fuel pump relay pin 86--->85. I'm guessing that is not going to be enough voltage to activate a 12v relay. Its strange because as I mentioned I can upload tunes with the smarty, no issues with the wait to start, I can read and clear codes etc. Does it sound like I have found it to you guys? Any similar experiences? Recommendations on testing or replacing the ECM? On to the VP. I drained my charged batteries today trying to get her started with the fuel pump relay bypassed (87--->30). I had injection lines 1,3,4 loosened. 4 spurted fuel immediately. 3 is weeping just the tiniest bit. 1 is still bone dry. I defintely have good fuel pressure 15+psi, and I cracked the vp return until had steady fuel coming out. It didn't take nearly as long to start when I actually installed the FASS when I first bought the truck. Ive read that if you aren't getting fuel spurting much quicker than that, you've got a dead pump. Sound correct? Thats a hell of a thing, to have an ECM and VP go out. Thanks guys

When I test from ECM 36 to its respective pin in plug/connector that plugs into the PDC I get a rock solid .1ohm. If I ohm from ECM 36 to relay 86, I get a weird reading, like 5 milliohms, but it fluctuates up and down. I will test it once again tomorrow, just in case I made some error. Thank you very much for that picture. I had not been inside that, I dont know why I assumed there was a circuit board.

Ok guys, tell me if this sounds reasonable. The truck was parked outside for almost two years. I had the hood slightly cracked for the trickle charger. I washed it periodically. I'm assuming there is a circuit board inside the box. I am wondering if it's feasible the connector for fuel pump relay 86, assuming it does interact with a circuit board, is corroded. I saw some pictures of third gens that had something like this happen. I wanted to know if this sounds like a likely culprit to you guys before I go digging into the PDC. My ohm reading from between the PDC connector and ECM connector seem to indicated there isn't a break or short between this two.

Ok, I have re run some of the tests once again. Something is up. For step #4 of the p0215 work I am getting a fluctuating reading of about 1.5 milli-ohm from relay 86 to ecm 36. If I test ecm 36 to the terminal in the PDC connector for the brown/white wire then I get .2ohm. Could that mean the problem is in the PDC?

UPDATE OK with the knowledge that I was using the wrong ground in some of the diagnostics, I re-ran the applicable parts of the p1689 and p0215 diagnotics P1689 1)check 2)No visual problems 3)FPCM #7 to passenger battery ground---No Voltage (.002V) --at this point it instructs to go to P0215, but I just finished the rest of the P1689 in case it gives any useful info 4)FPCM #6 to battery voltage ---12.5v 5)FPCM#2 to ECM 13 Less than 5ohm? Yes, .2ohm 6)FPCM#2 to ground-- No reading at all I stopped there and went to P0215. P0215 1)Battery voltage to Fuel Pump relay 85 ---Check, 12.5v 2)Relay reistance is good 70ohm 3)ECM 49 and 30 to battery voltage both show 12.5v 4)ECM 36 to Fuel pump relay 86 less than 10 ohm? Yes .3ohm 5)Relay 86 to passenger battery gound shows .5ohm. Guide says it should be 100ohm So thats where I am. That would seem to indicate that I need to repair short to ground in Brown/White wire between PDC and ECM. Any tips on how and where to start looking, or any further test I can do to make sure that is whats going on? Thanks!

Ok good. I thought it was probable that it had died anyway. Normally that wouldnt be good, but I have an II hrvp I never got around to installing on hand. Id rather do that work than chase gremlins!

Good grief, that explains a lot. No wonder I was getting some weird readings. I need to go back through parts of the 1689 and 0215 code diagnostics. Ive just been chasing my tail. Yeah, I'm just learning as far as electrical goes. Mechanical I am decent at, electrical is new material. Thank you for taking the time, I will report back. ETA one more thing...when I jumped the vp44, theres no reason it would be an issue that I had the leads going to the driver battery, would it be?

Thank you for the reply. Just to clarify (I am pretty green with solving electrical issues!) I want to test ECM pin 36 to a gound, correct. Dumb side question, the ground should be a chassis ground, not the battery, is that right? For the second part, I assume I would need to disconnect the brown/white at the pdc end. What is the best way to access that. I have never dug into the pdc before. Apologies for the rudimentary questions. Thanks Mopar1973Man

Hey guys, This is my first post over here. Id like to thank Mopar1973Man for having this forum and for all the information he contributes. The trouble code walkthoughs are an amazing resource. I am trying to resolve P1689 and P0215 DTCs. Truck: 01 QCLB CTD Auto 4wd. Pertinent upgrades: FASS system 95gph, smartry and original quadzilla adrenaline. There are lots of other upgrades, but none that should relate to my question. Backround: Truck was sitting for the better part of two years. When I stopped driving it, it was running well. When I came back to start it again, I had a no crank issue that ended up being a bad ignition switch. After that was fixed it will no crank but not start. It has fresh fuel and chraged batteries.No blown fuses or bad relays that I can identify. I checked for codes both on the odo and the smarty and I have a P1689 and a P0215. I had a link in my supply fuel line which I subsequently replaced, but those codes existed before and now after that ( I have read sometimes youll throw a P1689 after opening a fuel line). At this point I found the code diagnostics on this site and began to go through them. As a side note, I believe the VP44 is actually bad. I jumped it and still couldnt get the truck to fire. I do have fuel at the inj pump and the lines are bled etc. There is a secondary issue, and I am not getting voltage to the pump as you will see... P1689 After going through the first couple of steps, verifying the codes and checking the connectors are secure and there are no visually obvious breaks or problems I moved to step 3 to verify that I was getting voltage to pin 7 (red/grn) wire on the FPCM, I am getting .1v, so no voltage essentially, to pin 7. The guide then directs you to to the P0215 diagnostic. P0215 1) I have 12.5v to relay 85 2)Relay is good, has 70ohm and was taken from the horn slot which works 3)ECM pins 30 and 49 have 12.5v 4)Relay 86 to ECM pin 36 shows about .3 ohm 5)Relay 86 to ground gives me a reading of between .1 and .5 ohm. It says I should be getting 100 ohm or more. In the guide it states for #5 "If resistance is less than 100 ohms, repair short to ground in Brown/White wire between PDC and ECM." which seems to be the case. I am just looking for some reassurance that theres nothing else it could be. I cant understand how I could get a short in the wiring harness just sitting there for and extended time. Has anyone here experienced something like this? I just want to make 100% before I go tearing open the wiring harness. Does anyone have some tips or tricks on how to go about the repair? Would it make sense to tap the brown/white coming out of the pdc and coming out of the ecm connector to verify thats the problem first? Any insight would be much appreciated!