Brooks

eviltwisted1 My apologies, I had typed a reply that seemingly didn’t post. I did send a message to your Facebook account too. Nice work by the way, I used to help a friend of mine do that here where I am. Ultimate Concrete, it was called. Gratifying work. I would do the W-T ground mod for sure, it doesn’t take a lot of time and it’s worth the effort, If not for anything but to forces you to know the electrical side of these things, which you’re going to want to know anyway if you plan on keeping it. Also take the ground underneath your drivers battery tray apart. Mine looked good at first glimpse. So much so I put it all back together. Couldn’t sleep and woke up the next morning to take the battery tray back out again and look at the wires. There is 11 grounds on one stud. I had to cut back about 6-8” on most to find good copper to solder to. I’ll include a picture. Neither of those helped fix my P1689....but no doubt it will save me a lot of headaches down the road....and definitely should have been done. What did fix my code for now and at least a few starts (no driving yet) giving me the first glimpse of hope in the last couple of weeks was something in the 11 pin connector on the middle of the firewall (the one with the lock on it). I took this connector apart, probed for ground and 12v etc. Put it back together cleared my code and voila. Code was gone, check engine light too. It would start but still not rev over 2000rpm. In Park. However... Pulled it into neutral and no problems. Full throttle and rpms. Speaking with mopar1973man there could be something still going on with the neutral safety switch and the torque management system, not quite sure yet as I’m still celebrating my small victory in this fiasco and having full throttle and no p1689 I still have a 1693 companion code because one of our local transmission companies at one point cut one of the wires going to the transmission...it’s been that way since, I’m in the process of trying to decipher which one because it didn’t need to be done. The transmission wouldn’t upshift. Only had first and reverse. Their fix was to cut a wire, charge $700 and then blame it on the “truck side of things”. This was under warranty at the time btw. I left pissed, bought another rebuilt transmission from a different company and put it in myself. That was two years ago and it’s never missed a beat. Figure I may as well fix the wire they cut if I can find it as it definitely wasn’t the problem and perhaps be code free For now I’m happy that the p1693 doesn’t set off the CEL. I hate a dash that looks like a Christmas ?.

This is the step by step I was doing. I’m still going to be at a few things. Despite having gone through it. The Ground mod could perhaps fix it, worst case it’s all proper and it forces you to look places you haven’t where perhaps you could come across a broken or green wire etc. It’s not hard and only a few hours to do with minimal investment. Worst case, you get to know the truck better right lol. A friend of mine did the same type of work here in town. Ultimate Concrete. I worked on a few jobs with him. He just left for a job over in Cuba, Jamaica ...somewhere sunny to do the same thing before the virus struck. Good work but a niche market, especially under these circumstances.

Eviltwistedone. I like the user name. My buddy did a lot of welding etc a few years back and called his shop twistedsteel. Unfortunately I’m in no position to take it anywhere, so I’m forced to continue to learn, or attempt to learn and try a little more yet before I just park it and go on with life. Sucks as we just installed a new dump box and it is the busy season for my son who uses the truck for yard cleanups, soil, rock deliveries etc. The W-T ground mod did nothing to help my situation, although I’m sure if I get to the point of driving it again, it may help with a few other “ghosts” Mine acts perfectly normal, pedal response, start up, off idle etc...it’s basically Just the same as If someone switched the RPM chip in a rev limiter box to 2000. I’ve got through most of ‘73s flowchart more than once, with varying results, but so far all seem okay. Waiting to borrow a different meter tonight and another set of eyes/brain with a buddy tonight that’s a electronic tech. Everything I’ve learned from Mopar1973man and this site since buying this truck 10 years ago has never let me down yet.....I’m keeping faith before taking it to someone who condemns either the vp or the ecm without knowing for sure the problem. Look at how many posts that show...okay I spent a bunch of money and I’m no further ahead. Keep the faith, we’ll figure them out. ? So while checking waiting for the other meter, I got checking for continuity between the fuel injection pump and the ECM wires. Pin 3 at the Injection pump should go to pin 44 at the ecm. orange/brown at the ECM. I don’t have continuity. Pin 5 at the injection pump and pin 33 at the Ecm. Light blue/red wire. I don’t have continuity. I’m assuming I should, however not knowing what the data link shield inj is, nor did I realize we had a knock sensor return on our motors....can’t say for certain they should have continuity until I find out what they are. Just completed the step by step and have a problem at step 8. 8. Ensure ignition is off and FPCM harness connector and ECMharness connector are still disconnected. Using DVOM, measure resistance between ground and terminal No. 1 (Black wire) on FPCM harness connector. If resistance is 5 ohms or greater, replace and program ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If resistance is less than 5 ohms, repair short to ground in Black wire between FPCM and ECM. Im showing an open loop For this step. ?‍♂️

I have the same code P1689. I’ve tried swapping relays, I’ve done the W-T ground mod, just not the positive wire to the alternator as I’m awaiting a circuit breaker. Mine will start and run, idles great. Just won’t rev past 2000rpm. Good throttle response. I cleared the code, came back next start. Cleared it again and it hasn’t come back (yet). What I did find odd is with the grid heaters unhooked, look at the live stream values I’m getting for my ecm and injector pump voltages? I’m stumped so far. ?‍♂️ IMG_3230.MOV What I mean by won’t rev past 2000rpm. I give it a shot or two just to show you throttle response and then if you pin it....rev limits at 2000 IMG_3231.MOV

Sorry guys, I posted the other day with a P1689 Code, which is now gone and hasn’t come back. Starts and idles great. Sounds perfect, just won’t rev over 2000rpm. I assume just waiting to pop back up. While watching live stream I noticed these voltage readings. Any ideas as to why, or what’s up? Grid heaters are unhooked by the way. IMG_3223.MOV

I appreciate your assistance, after double checking the readings. I don’t really have a stable reading. It varies from 0.0 to 0.5. Up to 1.5 ohms on pin 30 vs ground at one point. but no open loop.

Hi Haggar, thanks for the response. I took my readings from the drivers battery ground. I’ll try a few others to see if I can get a different result.

As my first post, thanks for all you do for the rest of us...I appreciate you all more than you know. I’m going through the step by step for this code and have run into a snag at step 5. Looking for confirmation with someone else before I start cutting wires. By these results I’m guessing a problem with both my white and black wires between the FPCM and the ECM and I should replace both. (Ironically both these wires have a weird little twist coming out of the FPCM) FYI. Just finished the W-T ground mod. Waiting on a circuit breaker to do the positive side. If anyone could confirm my suspicions, i would greatly appreciate it. 5. Ensure ignition is off and FPCM harness connector and ECMharness connector are still disconnected. Using DVOM, measure resistance of White wire between terminal No. 2 on FPCMharness connector and terminal No. 13 on ECM harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, repair open or high resistance in White wire between FPCM and ECM. 6. Ensure ignition is off and FPCM harness connector and ECMharness connector are still disconnected. Using DVOM, measure resistance between ground and terminal No. 2 (White wire) on FPCM connector. If resistance is 5 ohms or greater, go to next step. If resistance is less than 5 ohms, repair short to ground in White wire between FPCM and ECM. 7. Ensure ignition is off and FPCM harness connector and ECMharness connector are still disconnected. Using DVOM, measure resistance of Black wire between terminal No. 1 on FPCMharness connector and terminal No. 23 on ECM harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or greater, repair open or high resistance in Black wire between FPCM and ECM. 8. Ensure ignition is off and FPCM harness connector and ECMharness connector are still disconnected. Using DVOM, measure resistance between ground and terminal No. 1 (Black wire) on FPCM harness connector. If resistance is 5 ohms or greater, replace and program ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If resistance is less than 5 ohms, repair short to ground in Black wire between FPCM and ECM. Step 5 I’m showing 0.1 ohms resistance (Continuity) Step 6 I’m showing an Open Loop Step 7 0.0 ohms (continuity) Step 8 open loop.