teknic

I’m thinking this will be the final update. After my most recent post the issue reoccurred in the next few days but only when idling for a bit and it would go away quickly. at this point the tach hasn’t stopped working in over 2 weeks even when idling. my only thought is oil was wicking thru the harness and into a connector enough to confuse the system. Now that the leak has stopped and it’s been driven a while all the oil is gone and no longer causing me any issue. when I started diaging this I never would’ve thought of this conclusion. thanks for all the help!

Ok guys so it’s been ages but I’ve finally got an update…. And it’s one I didn’t expect. with first nice weekend weather I decided to finally replace my Tappet cover which has been leaking for years and finally got bad enough that I’d lose multiple quarts in a drive. did the whole job, following a guide here, installed a Keating Billet Tappet cover and bypassed my OEM fuel filter that I hadn’t used in years. since finishing that job my tach and other gauges began working. Thinking it was probably just random I didn’t pay much attention to it. However today the CEL went off by itself and I realized my gauges haven’t died in about a week. It’s never made it more than a day. so, knock on wood, I may have fixed it. The exact cause no clue, possibly oil getting into ECM? Oil misting into connector and messing with signals? Maybe just disassembling, cleaning and reassembling that area? Who knows, but I’m actually hoping it’s finally solved. wanted to be sure to post here in case anyone else is going through something similar. thanks for all the help, here’s hoping it’s actually fixed!

Truck sorta fell to back of my list, still planning on updating this but so far I have done nothing new

Small update as I’ve been dealing with random stuff, acquired the necessary file from Smarty to flash an ECM with my trucks factory files. Anyone interested in it you contact sales@smartyresource.com and they’ll help you out. Price is up to $150 at the moment. bought the 2000 truck, registering it on Saturday and then get it home and hopefully swap the ecm and see what happens. will update when there’s news

Bit of a detour to the plan, ran across a deal I couldn’t pass up a 2000 2500 Cummins shortbed with the gray interior I was looking for, guys asking 3500 so going to be picking that up probably for 3200 Then I found a Smarty s-03 for $350 and contacted smarty who said they can provide me a file to reprogram that 2000 auto ecm to a 2001 6speed ecm. So once I have both here I’ll swap the ecm over and see if it fixes it. Fingers crossed that it does, then I’ll just get any ecm and flash it to the 2000 truck and steal its interior and turn it into a farm truck. if it doesn’t fix it I’ll ship my pcm out to ACS and go from there feel like I need to start a build thread.

Oh and it’ll probably be a few weeks before I send it out, need to pick up another door and a nice dark grey interior for the truck restoration progress.

Lol I threw an ECM at it once hahaha but I tested before that too, just not as thoroughly. Think I just got a badly rebuilt ecm. On the bright side I now know a lot of the wiring. I’ll definitely keep this thread updated on outcome

Ok so I think I’m going to send my ECM and PCM out to “Auto Computer Specialist” and see what they find, hopefully they can recreate my issue and I can get this solved and onto better ways to spend my time on the truck. while it’s down I’ll prob finally swap the dash and all the HVAC stuff plus sound deaden and install my new black carpet

Ok quick update pulled my radio and HVAC panel… 2 pin CCD Connector nowhere to be found, see pic attached. Pulled back that wire covering too, no cut wires no loose wires nothing. If anyone out there could get a picture of their radio C3 connector and see/show where it comes from in the harness id be immensely grateful. Mainly need to know where it comes from, because if it comes out the same spot as the end of that red circle I’ve got no clue where this plug went Update: Alright I decided to pull out Junction Connector 7, to the left of the steering wheel which is where all the CCD lines join. I looked at pins 17 and 20 which is where Radio C3 should terminate, they’re not there. I think my truck just doesn’t have that connector, let me know if I’m wrong.

Alright I’ll rip into it and report back, I know there was no connector so I’m sorta thinking/hoping someone clip the wires somewhere and they’re randomly shorting Just posting this pic for my own and others references, the radio ccd connector is “Radio C3” in service manual. Located in Figure 25 of connector locations. (Figure is from angle of you looking from firewall towards radio) in the figure you can see it should branch off the C1 and C2 bundle just a few inches before the C1 and C2 connectors.

That’s so weird I even just pulled up the service manual and see the radio C3 connector with 2 pins. well I guess I’ll be tearing in there later maybe that thing is crushed somewhere. do you know if it’s bundled with the 2 main radio connectors?

ok yea so my cluster definitely shows no codes after the test, so it’s good. Hm I couldn’t find any extra plugs at my radio, would this 2-pin connector be in the same bundle as the other 2 connectors? I have no audio controls on my steering wheel, just cruise control. I have 2 connectors that are like 6-7 wires each that go to radio, 1 antenna lead, 1 wire that is single pin slip on connector like how you see on oil oil pressure sensors, and then a big round plug that I think is the 6-disc changer. I tried reaching around and didn’t find any loose wires. Any chance you have a picture for reference?

Ahh ok yea I’ve never seen those pop up at all

Attached are the codes the cluster shows. yea I’m thinking the ECM and PCM need to get tested and gone over. Going to do the WT wire Mod first for the hell of it.

Yes while the 3 gauges were dead I performed the cluster test, all needles moved correctly and at the end it saw codes p1693 and p1694.

Ok thanks, if you saw above I did as suggested running engine just off ecm/pcm/cluster and the tach stayed dead. I guess next thing I’ll do is the WT wire mod in case it’s a ground issue

Checked AC from alternator stud to the negative terminal of both batteries, both showed same result .03-.04. Only other way I could do it is from alternator stud to engine block I guess? I’ll certainly do the WT mod but I don’t think that’ll fix my issue, it’s more of a preventative. Before I spend any big money I will do the mod though, already got the 150A circuit breaker. BTW should my CCD voltages have been exactly 2.51 and 2.49? Is the fact they’re 2.49 and 2.42 a sign of the issue or just normal variance?

oh and something I didn’t note earlier, when I had the harness apart moving it around didn’t trigger the tach to come to life/die

Ok so can’t find the Radio CCD lines, I have an aftermarket radio so not sure they exist anymore but I unplugged my radio, ABS and overhead console. Started truck, tach dead. I’m working on getting to airbag module, haven’t taken off the shifter tower before so may be a minute. I also reached in and made sure all connectors were fully seated to interior fuse box, they were. Also pulled apart the underhood fuse box, no signs of any corrosion or messed up wires down there Altho admittedly it’s hard to see Alright got Airbag module disconnected, ran the truck, gauges still dead. So this at least narrows it down to wiring/ecm/pcm/cluster correct?

So disconnect everything on CCD besides cluster/ECM/PCM and just monitor to see if gauge issue occurs while heating/cooling/shocking ecm?

Ok now to PCM connector tach dead, issue present. Pulled all 3 PCM Connectors, visibly they have no signs of damage, all pins look to be fully seat to the connector. All this is with Key Off, Battery Connected. 6th Test - PCM C3 Pin 28 to OBD Pin 3 - 119.7 ohms, didn’t fluctuate at all PCM C3 Pin 28 to OBD Pin 11 - 0.8 ohms PCM C3 Pin 30 to OBD Pin 3 - 0.5 to 0.6 ohms PCM C3 Pin 30 to OBD Pin 11 - 119.9 random spikes down to 102 ohm 7th Test - PCM C1 Pin 31 to Ground - 0.2 ohm I also started pulling the harness wrap apart starting at PCM, only found the violet wires splice and that was over the valve cover, the white wire splice must be closer to the 2 connectors by the vacuum line. Still going over stuff at the moment. After doing all this and then reconnecting the dash came back to life, gonna let it idle and see if it reoccurs or maybe the area I was testing is the issue. (I’m doubtful tho) update: dead again So now that it’s dead again I recheck Pin 3 and Pin 11 at OVD I have 2.48V and 2.42V is this off by enough to be an issue? Based on all this info does anyone have any ideas? I feel like these readings seem to be okay not sure what my next step would be, I mean the one CCD like has a smidge extra resistance but it doesn’t jump around. I’m sort of worried about the clusters 120ohm resistor that when I test the one direction randomly drops to 102ohms. Not sure if it’s time to send my ecm and pcm out to be tested

I did pull and separate the 2 connectors by the vacuum tee, didn’t see anything abnormal on them and so put them back together. I’m going to be moving to testing the PCM connector today, thanks for the splice info I’ll be sure to check those out also. I’ll put together another list of things soon. im just trying to document all these things because it seems like a common issue that has pretty limited detail info on it out on the web. So hopefully I can fix my issue and help someone else down the line one day.

Ok first chance to look at stuff. For starts I’m using a Fluke 88V which I know is balls on accurate, I regularly use it to trace amperage draws and such at work (mechanic) measure from Alternator stud to negative terminal (on both batteries) .030-.040 AC voltage. Watching dashboard as tach died and came back there seems to be no correlation towards higher AC turning tach off. While monitoring the AC voltage though the tach issue seemed to occur often but that could be random 2nd Test- my tach is dead during this test, Key On Engine off. Ground to OBD2 Pin 3 - 2.49V, Ground to OBD Pin 11 - 2.46V checking resistance across Pin 3 and 11 of OBD is showing 60.6 ohms, with minor fluctuations (key off, batteries connected). Biggest fluctuation was dropping to 52 ohm very fast before going to 60 again think this means the network is good voltage-wise. Resistance I’m not sure of. I’m open to opinions tho. 3rd Test - With tach dead perform cluster test, everything functions properly. All needles work. Only codes showing on cluster are P1694 and P1693, p1698 only shows on my Edge unit I guess 4th Test - Pin 30 ECM to Drivers Battery Ground - 0.5ohms, to Pass Battery - 0.4 ohms 5th Test - ECM Pin 40 to OBD Pin 11 - 0.6 ohm ECM Pin 40 to OBD Pin 3 - 60.4 ohm drops to as low as 52ohm randomly but not often ECM Pin 41 to OBD Pin 3 - 0.9 ohm (not a fan of this) kept monitoring it settled at 0.6-0.7 ohm by itself but definitely keeping this on my list Ecm Pin 41 to OBD Pin 11 - 60.6 ohm (didn’t sit and watch it long) going to end testing there for tonight. I’m a little suspect of ECM Pin 41s resistance to OBD Pin 3, also not a fan of the CCD resistance randomly dropping to 52 ohms I may need to test that more

All right i will add it to my todo list while diagnosing this.

Where would I put the 150A circuit breaker? Just between the new alternator to passenger battery wire? haven’t had a chance to check things out, tweaked my back a bit and combined with this 94 deg 100% humidity weather I can’t convince myself to work on the truck atm. but I’m compiling all this stuff to check/do once the weather breaks