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Does the harness that the nss connects to tie into the tcm?
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Mar 20, 2020 23:35
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 00:21
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Fused ignition voltage is always 12v. Voltage is correct. There are two versions of the AW4 NSS, the 98+ has extra pins apparently so it can tell if the NSS is bad or its an overdrive problem. There are guides on cleaning the old one if you want to try that. I really think your issue is the TCM. Cursory research indicates you can drive with it unplugged but will only have two gears and need to shift manually. If you get to the point where its not shifting or the gauges are acting up, unplug the TCM. The odometer and gauges that are going crazy are all ccd bus signals.
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Mar 21, 2020 02:27
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 04:16
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You might be surprised. If that TCM is shorted and pulling the 5v bus down, it very well could be tricking the alt/gas gauge and other sensors on the bus. I forget, did you check voltage on the 5v lines when the vehicle is acting up? Edit: on second thought, how have you determined that the vehicle is overcharging? Multimeter at the battery or the gauge? rdb fucked around with this message at 13:45 on Mar 21, 2020 |
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Mar 21, 2020 13:36
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 18:10
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Yikes. So its still overcharging with the TCM unplugged. That rules out the two issues being related. It may be multiple issues. In the mean time: https://youtu.be/fvP5btMD1aM This shows the kinda weird issues a ccd bus fault can cause. Can you unplug the instrument cluster and see if it still overcharges?
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Mar 21, 2020 19:03
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 19:22
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Nothing to do with ground. The rke module in the dome lamp was the cause. It was bridging the dome light voltage with the ccd bus and making everything go nuts. Your airbag module is suspect as well, since the light appears to be on. Maybe do the instrument cluster last and start with the easy ones, RKE and airbag Wait, I didn’t watch that until the end. It was a bad ground. But still, when he unplugged that rke module the problem went away. And yeah don’t disconnect/reconnect the airbag module with the battery hooked up. rdb fucked around with this message at 20:04 on Mar 21, 2020 |
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Mar 21, 2020 19:24
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I don’t think the fan would do it. It shouldn’t be running 30 seconds after startup. https://mopar1973man.com/cummins/ar...-data-bus-r329/ This explains ccd bus and what problems it causes. Can you pull airbag codes? Obviously with the passenger bag removed it should have one.
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Mar 21, 2020 19:40
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My line of thinking: the alternator output is controlled by the PCM. The original pcm tested ok, and a second known good pcm did not fix the issue. So the PCM is doing what it thinks is correct. So why does it think it needs to overcharge? Where is it getting its information from? The gauges freaking out are definitely a ccd bus issue. The information the gauge cluster displays come from the CCD bus. A bad ground between the PCM and alternator could make the PCM think voltage is too low and it needs to overcharge. It looks like the PCM is bolted to metal and gets its ground that way, alt grounds to engine block, and you said the ground there was good. If you suspect a weak ground to a fuse block/dashboard,engine a jumper wire from the suspect part to a chassis bolt will clear things up. I don’t think its a ground because you have been over all of them before. So the ECM is probably getting bad info on system voltage from somewhere else. Since the CCD bus is freaking out on occasion I think that may be the culprit. The XJ is no BMW with 100 different modules on it. Isolating them should be straightforward.
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Mar 21, 2020 19:54
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 20:06
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Krakkles posted:RKE and Airbag definitely both suspect - RKE is wrapped in tape and tucked above a custom light mount, so it could easily be having some sort of issue. I'll unplug that one first, since I think it's easier to get to, and go looking for the Airbag module as well. Unhook the battery before you unplug/reconnect the airbag module.
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Mar 21, 2020 20:08
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 21, 2020 20:23
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 21, 2020 22:46
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Krakkles posted:RKE module, no dice. Looking up instructions for Airbag Control Module right now, but just to make sure - the plan is, disconnect the battery, disconnect the ACM, reconnect the battery, see if the problem recurs? Yeah, I would try that. Same with the overhead console module. If those don’t work maybe the instrument cluster itself. There seems to be a lot of reports of bad instrument cluster harness connectors.
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Mar 22, 2020 00:02
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 22, 2020 06:19
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Krakkles posted:It looks like voltage is probably monitored via the Generator Field (+) wire (first image in this post), as that's fed directly from the alternator to the PCM. I opened up the back of the PCM connectors, back probed that wire, and proceeded to dick around with stuff for about 30 minutes while it absolutely did not overcharge. It was later in the day, so assuming I'm right about temperature playing a part, that may be why. Dropping in as someone with no domain specific experience, but with a good idea still of how generators of this nature work... The "field" wires are how the PCM tells the alternator how much powaahhhh to put out. The idea is that you put a small amount of current into the field wires (current flows from "field +", through the alternator, and out into "generator driver"), and you get a lot of current out of the generator. So you wouldn't be sensing from the generator field connections, but those connections do tell you how much power the generator is being commanded to make. From your copy and paste, "This is done by cycling the ground path to control the strength of the rotor magnetic field.". This tells me that the + wire should always be connected to battery voltage, so it's not a surprise that the + is always at 15.8V. But the "generator driver" wire (not the "field +" wire) should vary between 0 and 14V -- when the PCM is asking the generator to pump out as much as it can, it will be close to 0, and when the PCM is asking the generator to do nothing, the wire should be around 14V. Presumably the PCM is sensing battery voltage through its own + and its own ground. This all kind of points to the idea of a bad PCM ground (which would explain it getting confused and commanding the alternator to full rear end in a top hat mode, but doesn't explain why it lets the battery droop so bad to begin with). When the rest of the battery bus measures at 15.8V, I'd be interested to see what that measurement looks like as close to the PCM as possible (ideally, inside the PCM if you can) -- between V+ on the PCM, and V- on the PCM.
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Mar 22, 2020 08:50
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 22, 2020 09:16
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 22, 2020 20:12
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 23, 2020 23:22
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 25, 2020 03:30
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Hows the battery ground?
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Mar 25, 2020 15:33
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Krakkles fucked around with this message at 23:25 on Mar 15, 2022 |
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Mar 25, 2020 15:56
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Is there any direct connection from the battery negative to the pcm? Other than body grounds.
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Mar 25, 2020 16:34
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Charging issues are a common enough issue on Mopar that there's plenty of companies that make standalone voltage regulator kits. Here's one that turned up on Google. I can't vouch for them, but they claim to (usually) be able to keep the CEL from coming on with it. I'd much prefer fixing the issue properly, but you've already replaced the alternator, battery, and PCM. It's gotta be something either really obscure, or something buried in the harness.
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Mar 25, 2020 17:31
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STR posted:Charging issues are a common enough issue on Mopar Just as rust is measured in Sockingtons, Mopar charging issues are in Javids.
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Mar 25, 2020 17:40
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STR posted:Charging issues are a common enough issue on Mopar that there's plenty of companies that make standalone voltage regulator kits. I think the guy with the broken ram van (Javid) uses one of those. I don’t know if that would fix the lost shifting.
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Mar 25, 2020 17:43
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Javid's was a hack job (and that's putting it nicely) by the PO though, this is a relatively straightforward kit. There's no telling what's going on with the shifting until it stops overcharging. Maybe unplug the field connector and drive around a little bit (during the day and with all accessories off, no heat or AC)? You'll be running purely on battery power, so you don't want to do this for more than, say, 15 minutes, but if it shifts fine, then you can probably start considering that the shifting issues are caused by the overvoltage. randomidiot fucked around with this message at 17:46 on Mar 25, 2020 |
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Mar 25, 2020 17:44
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 25, 2020 17:52
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 25, 2020 19:13
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https://autoprollc.com/wp-content/uploads/2016/12/5-RemyTechnicalBulletin_July_web.pdf This explains how it works.
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Mar 25, 2020 19:24
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Krakkles posted:it definitely shifts fine when it first starts, and the onset of loss of shifting matches the first time in overvolts in every case I've observed. The fact that the voltage is kicking up high enough to gently caress with the rest of the electronics is pretty telling, IMO. Electronics can usually handle overvoltage better than undervoltage, but 17-18 volts is considerably over the ~13-15 volts they're expecting when you consider they're expected to work with as little as 10-11 volts. Still, if the rest of the electronics have survived, the TCM probably has as well (maybe with a severely shortened lifespan). I'm no engineer, and no Mopar toucher, just a shadetree guy that happens to know a little more about electrical than most shadetree types (but not a ton more) - rdb or kastein would certainly be more knowledgeable. I'm just basing this on my own experiences with pissed off charging systems. randomidiot fucked around with this message at 20:27 on Mar 25, 2020 |
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Mar 25, 2020 20:25
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 25, 2020 21:13
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Yours is figure 5 single field. Sorry, should have included that.
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Mar 25, 2020 21:22
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Krakkles fucked around with this message at 23:27 on Mar 15, 2022 |
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Mar 25, 2020 21:27
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If you want, consider de pinning or cutting the driver wire at the pcm and running a jumper straight to the generator driver (K72). The other just to bat+. See if it fixes it. While its cut or de pinned you can check and see what voltage its putting on the field wire at the PCM. Last edit: be sure to leave enough wire if you cut to splice back together. rdb fucked around with this message at 22:47 on Mar 25, 2020 |
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Mar 25, 2020 22:26
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Could you post a picture of the battery terminals? Are there any added accessories connected to the battery +?
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Mar 25, 2020 22:31
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Krakkles fucked around with this message at 23:26 on Mar 15, 2022 |
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Mar 26, 2020 00:33
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Krakkles posted:Eep, scary. The terminals look good, nice job wiring. Did I give you the wrong pin? The one thats .6 at the alt is k72? And its showing 12v at the pcm?
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Mar 26, 2020 00:43
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