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!

 

3 hours ago, JHFIII said:

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

I'm sure it's possible but I would just run it on the outside then you know what it's for, I'm guessing that's for your lift pump right. some people just bypass ECM all together and run lift pump off a toggle switch through a relay, the only problem with that I heard off is safety in case of an accident. That and forgetting to turn it on or off, maybe get a toggle with LED built into it.

Edited November 1, 20177 yr by Dieselfuture

7 hours ago, JHFIII said:

5)Relay 86 to G100 ground = 65ohm

 

Too high... I would chase that ground connection. That should be 0 Ohms. So it might not be pulling the relay closed all the way. 

5 hours ago, Mopar1973Man said:

 

Too high... I would chase that ground connection. That should be 0 Ohms. So it might not be pulling the relay closed all the way. 

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.

JHF,

 

If you were actually checking 86(this is the ECM output to fire the relay) to ground (ignition off.... ignition on would/should blow your meter) you could get a couple different readings.  with the relay in the socket, you would read resistance through the coil which should be in the range you said.  If you did it with the relay removed, you are reading backwards through the ECM and power supply.... it will be an odd reading.

 

Where did this diagnostic list come from?  I can't find it in my manual.  I would like to read what/why they are looking for.

 

I have attached the FSM page for the relay. 

 

To diagnose this system, I would:

1) remove relay. 

2) with the key on, put the black meter lead to ground (a good ground) and put the red in 86.  You should have 12v.

3)  have someone turn the key off while reading this.  The 12v should go away.  recycle the key on. it should come back.

4)move the red lead to cavity for 30.   This should have 12v whether the key is on or off. 

5)make sure key is off.  put meter on ohms.  touch red and black probes to each other.  This should read about 0.1 ohm or so.

6)put black lead on good ground, put red lead in 85.  You should have about 0.1ohms or so again.

7) Disconnect the wiring harness from the VP 44. 

8) with the black placed in 87.  put the red on terminal 7 (red / light green) at the injector pump.  this should read 0.1 ohm or so.

 

You have now confirmed that the

1) ECM is outputting 12v when it is supposed to.

2) fuse 3 is ok.

3) the wire between 85 and ground is good. (this will let the relay shift when commanded)

4) the wire between 87 and the injector pump is continuous.

 

The only thing we have not proven is that the VP44 is "seeing" the signal sent.  But if all the above checks out, it should be close.

 

The only other test we could do is put the relay back in and check Terminal 7 to see if it gets 12v.  but that would require the VP44 be disconnected, and it is possible that will throw other codes.  (if needed we will talk about how to set up a back probe.... but that is scary for weather proof type connectors.) 

 

HTH

 

Hag

 

 

2001 FSM Ram 8w-30-37.pdf

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.

JHF,

 

Thanks for the link.   Step 5 exactly "100 ohms" is not important.   The reason is:  You have both ends of the wire disconnected.  You are then testing that wire to ground, looking for a short in the wiring.  When they say "greater than 100 ohms" this goes to infinity and even open circuit.  (it should be an "open circuit"  That wire should not go to ground anywhere.)  the technical writer was trying to compensate for technicians with poor troubleshooting skills, improper meter set up etc. 

 

It looks like in an earlier post  you say you read  (with ECM disconnected and relay removed) from the socket for pin 85  to ground less than 100 ohms. (you have shown a couple different readings there.) 

 

This is a big part of the problem.  (My meter reads O.L. when the leads are not touching.) with relay removed and ECM disconnected  when you measure from cavity for 86 with the red lead, and the black lead on the negative battery terminal you should see O.L. or whatever your meter reads with the leads not touching anything.  The brown/white wire should NOT be touching ground anywhere.... If you see any other reading than O.L. it is touching ground and is wrong.  (you will find the insulation on the wire is rubbed through somewhere.)

 

HTH

 

Hag