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Krakkles fucked around with this message at 23:22 on Mar 15, 2022 |
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Mar 11, 2020 01:15
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Krakkles fucked around with this message at 23:22 on Mar 15, 2022 |
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Mar 11, 2020 01:15
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Given that you've already listed most of the items I'd default to checking, I have two considerations: intermittent harness problem (probably power or ground) to the PCM, or a module such as the cluster internally faulted and sending garbage data to the PCM it doesn't know what to do with/interfering with the PCM's power somehow. If the PCM does control the alternator voltage, and the voltage regulator circuit loses power, I'm guessing it would just cease regulating and your voltage would skyrocket. You say the PCM tests good, have you actually tried a new PCM to see if the problem persists? If the voltage regulator has an intermittent failure allowing the voltage to go that high it could very well cause all sorts of persistent and infuriatingly nonsensical problems all over the vehicle.
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Mar 11, 2020 03:46
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 11, 2020 04:33
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The nature of all of the faults scream power, ground, or control issue to me. I'm leaning on the PCM or PCM harness being at fault. Does the PCM have to be programmed or is it a straight drop-in?
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Mar 11, 2020 11:38
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Krakkles posted:The bold part is accurate - the PCM does control alternator voltage. That's not a bad idea. It did occur to me that when I sent the PCM in to get tested, they may well simply not have tested it long enough or in the particular fashion that would induce the problem - it DOES lately seem like heat is more of a factor, so totally plausible. Yeah the ebay one might cost you some $ - but if swapping it doesn't resolve your issues then you can just put it right back on ebay in the same packaging and the cost to you will be minimal/zero - and if it does fix it then from your checklist it looks like it will be totally worth it!
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Mar 11, 2020 12:51
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 11, 2020 15:16
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XJ Spotted. Thread rules.
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Mar 14, 2020 18:25
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How did the 5.4 swap go? What sort of adapter is needed to fit one in a Mustang? I thought mod motors were mod motors, they're all the same...
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Mar 15, 2020 01:15
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 15, 2020 02:56
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Krakkles posted:The bold part is accurate - the PCM does control alternator voltage. That's not a bad idea. It did occur to me that when I sent the PCM in to get tested, they may well simply not have tested it long enough or in the particular fashion that would induce the problem - it DOES lately seem like heat is more of a factor, so totally plausible. The random poo poo would make me think TIPM, except a 2000 doesn’t have that yet. Pull apart the fuse boxes and look at the bottom side. Is there one under the hood?
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Mar 15, 2020 14:37
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 15, 2020 20:24
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 16, 2020 02:05
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 17, 2020 21:33
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 19, 2020 02:25
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Krakkles posted:Annnnnd, nope. Oh, what a disappointment. I thought being at least partially confident was ok. Well, for a full harness check, I'd start at one place - probably the PCM - and just check along the whole harness with my eyes and hands. If there's no easily detectable trouble spots (chafe points, suspiciously flexible or stiff sections) I'd probably start trying to unwrap the harness. That is the lovely time consuming part and might again not turn up anything actionable. Wiring problems, especially intermittent, usually won't be uncovered by continuity checks. If there's an intermittent short between a power and signal wire, continuity checks to ground from the PCM end of the harness will be good and won't turn up anything suspicious. There is the potential of something else on the PCM's 12v input line loving up and causing a voltage drop that is enough to trip the PCM to shut off momentarily. Are you able to post the PCM wiring harness diagram, with its power inputs and grounds?
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Mar 19, 2020 12:58
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Krakkles fucked around with this message at 23:23 on Mar 15, 2022 |
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Mar 19, 2020 15:43
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Can you post a few diagrams? Alternator connector and charging circuits. What actually regulates the alternator output? I did some cursory investigation and it looks like the circuit goes through the instrument cluster. What regulates the position of the iac?
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Mar 19, 2020 16:43
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 19, 2020 17:38
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Or the battery temp sensor.
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Mar 19, 2020 17:57
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 19, 2020 17:59
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It says temp data along with monitored line voltage. What is that circuit like? I almost wonder if its the instrument cluster itself.
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Mar 19, 2020 18:42
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 19, 2020 19:13
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Krakkles posted:I don't think it's the cluster, but I welcome correction. Here's the instrument cluster diagram: I still think its the cluster messing with voltage somehow. https://www.cherokeeforum.com/f2/what-sensors-ccd-bus-239586/ I can’t explain why I think its the cluster because I looked at the wrong diagrams before. It could be anything on that ccd bus messing with voltage. You can try unplugging components one by one and look for a change. Edit: what does the 5v reference voltage look like? I bet its the source of some of the bullshit. rdb fucked around with this message at 19:24 on Mar 19, 2020 |
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Mar 19, 2020 19:20
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Re reading your symptoms, loss of automatic shifting. It still doesn’t shift? Can you communicate with the TCM or any other module on the bus? I would really like to unplug modules and see what changes, starting with the TCM. Low 5v reference would explain most of the symptoms with the gas gauge and IAC, lovely signals on the CCD bus would explain the gauges freaking out maybe the surging too. rdb fucked around with this message at 19:38 on Mar 19, 2020 |
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Mar 19, 2020 19:33
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 19, 2020 21:06
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Yeah, when the problem is occuring, unplug things one by one and note the changes. It could be any module or sensor pulling down the 5v reference. Instrument cluster as well. Since its loving with the gauge readings, which appear to come from data on the ccd bus, I would suspect its one of those modules doing both. But that could be wrong, could just be an intermittent shorted sensor somewhere causing everything to go nuts since they all run off 5v. I would literally try unplugging everything you can and see what changes. All the modules and sensors. That ccd bus will require an oscilloscope to check. Hooking a multimeter up to it wont tell you much, unless its totally dead. rdb fucked around with this message at 21:31 on Mar 19, 2020 |
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Mar 19, 2020 21:29
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rdb posted:Yeah, when the problem is occuring, unplug things one by one and note the changes. I'm no expert but if it was a sensor loving about then wouldn't most of them likely trigger a CEL with a recorded error code? How much poo poo can you unplug and still start the car?
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Mar 19, 2020 23:24
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 00:00
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Tomarse posted:I'm no expert but if it was a sensor loving about then wouldn't most of them likely trigger a CEL with a recorded error code? It really depends on how that sensor/module pulls the voltage down or fucks up the com line. It could be something you wouldn’t expect like the RKE module. Since we don’t have an oscilloscope or chrysler drbIII its going to be challenging to figure out whats actually going on. Look up diagnose dan on youtube. He explained recently how a door handle caused a no start on a bmw. Others couldn’t figure it out so they just unplugged the module the door handle connected to. No CEL from that. Cars can run with a lot of things unplugged. That jeep might not like not seeing the SKIM but it should run with without the rke module, instrument cluster, tcm, etc. Same with sensors, they can estimate airflow without the maf, guess where ignition timing should be without a cam sensor. They might run lovely, but if you unhook one and all the sudden it shifts or the gas gauge is accurate your probably on to something.
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Mar 20, 2020 00:06
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 00:09
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Krakkles posted:This might be a dumb question, but would something like this provide sufficient information to help? I'm not going to buy a $300 oscilloscope, but if a $30-50 unit will help at all, I'm more than down. It will help in that you can see what the signal looks like. It won’t tell you exactly what module is having the issue. A scan tool with the ability to communicate with all of them would. I am not sure what a DRB3 costs.
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Mar 20, 2020 00:25
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Krakkles posted:This might be a dumb question, but would something like this provide sufficient information to help? I'm not going to buy a $300 oscilloscope, but if a $30-50 unit will help at all, I'm more than down. You can get a cheap USB oscilloscope too - it is just a box with probes and it displays in the software on a laptop. I bought myself one to diagnose issues with a single sensor. I'm not sure you are there yet - but they are handy to have!
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Mar 20, 2020 00:32
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 00:37
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 This is the diagram for the CCD bus. Not a whole lot on it. It should be easy to isolate individual modules and see what starts working. We know the PCM is good, SKIM will prevent it from running for more than 2 seconds so that might be difficult. The person you bought the flashed ecu from might have disabled it.
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Mar 20, 2020 00:44
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It may even be the TCM itself. Monitor the voltage on that ccd bus and the 5v reference when you disconnect it.
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Mar 20, 2020 00:49
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 02:16
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I skimmed the thread so forgive if I'm suggesting something you've already done...But I would start at the CEL and work backwards since it's the best thing you've got to go off of. Check the wiring (use diagram and check resistance from one connector to the next all down the line and make sure it's good). Still screams ground to me, so see if there's a common ground on a lot of the things that are tripping up (cluster, etc.). You might just have a chaffed wire somewhere and might just require ripping a lot of poo poo apart to find. 
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Mar 20, 2020 13:17
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 18:45
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Krakkles fucked around with this message at 23:24 on Mar 15, 2022 |
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Mar 20, 2020 23:07
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