dbm7

Which solenoid? Why was it changed? Again, why was this done? ...well, these wear..but ultimately, why was it changed? Did you reset the idle voltage level after fitment? I'm just a tad confused ~ the flash code doesn't allude to these items being faulty, so in my mind the only reason to change these things, would be some drive-ability issue....and if that's the case, what was the problem? Those questions aside, check if the dropping resistor is OK ...should be 11~14 ohms (TCU doesn't throw a flash code for this) ~ also, these TCU designs have full time power (to keep fault code RAM alive), and I think that'll throw a logic code (as opposed to the 10 hardware codes), if that power is missing (or the ram has gone bad in the TCU, which you can check..but that's another story here perhaps).

Bit of a pity we don't have good images of the back/front of the PCB ~ that said, I found a YT vid of a teardown to replace dicky clock switches, and got enough of a glimpse to realize this PCB is the front-end to a connected to what I'll call PCBA, and as such this is all digital on this PCB..ergo, battery voltage probably doesn't make an appearance here ; that is, I'd expect them to do something on PCBA wrt power conditioning for the adjustment/display/switch PCB.... ....given what's transpired..ie; some permutation of 12vdc on a 5vdc with or without correct polarity...would explain why the zener said "no" and exploded. The transistor Q5 (M33) is likely to be a digital switching transistor...that is, package has builtin bias resistors to ensure it saturates as soon as base threshold voltage is reached (minimal rise/fall time)....and wrt the question 'what else could've fried?' ....well, I know there's an MCU on this board (display, I/O at a guess), and you hope they isolated it from this scenario...I got my crayons out, it looks a bit like this... ...not a lot to see, or rather, everything you'd like to see disappears down a via to the other side...base drive for the transistor comes from somewhere else, what this transistor is switching is somewhere else...but the zener circuit is exclusive to all this ~ it's providing a set voltage (current limited by the 1K3 resistor R19)...and disappears somewhere else down the via I marked V out ; if the errant voltage 'jumped' the diode in the millisecond before it exploded, whatever that V out via feeds may have seen a spike... ....I'll just imagine that Q5 was switched off at the time, thus no damage should've been done....but whatever that zener feeds has to be checked... HTH

Need to see other side of PCB in that area...ie; I don't see any thru-hole mounting, just soldered vias (smd zeners in SOT23 have 3 legs but only 2 are used, as reflected by PCB tracks)

That's not a transistor --- it's marked ZD1 which makes it a zener diode. As to what the breakdown voltage is, not enough there to divine.

The screw is for idle (pilot circuit) mixture adjustment. Else, I'm confused ~ the diagram shows 2 carby ports, and the intake manifold port, but you're suggesting the "2nd port on the back of the carb that isn’t mentioned in the diagrams" ...yet, both carby ports are shown...que?... ...in any event, that port should be connected, but if not (like it is now), it's unlikely to cause a backfire out the carby (it would introduce false air and give you a fast/lean idle) ...sounds more like timing issues/spark plug wire routing responsible for the backfiring.

The values for HID colour are also defined ~ see https://www.legislation.gov.au/F2006L02732/latest/text ~ goto section 3.9 onwards ....

...very much sounds like it ~ my subaru does the same noise & I know it's heat shield lose around CAT doing it...

Best guess would be light (combination) switch....but here's the wiring diagrams... https://mega.nz/file/6VR1nQpS#OluHuuezNX-K9A9HxbpjmTaSxQ1dsTuOjY1FQcI1Ymw https://mega.nz/file/ScJ2mQSR#70fgte2VGiQxFCPzaOu6JhtY1Y2zie_Xu7AsAFmPQis

All the schemas I can see, indicate your typical setup of ATF 'cooler' (read: heat exchanger) in the bottom radiator tank..ie; https://nissan.epc-data.com/stagea/wgnc34/5413-rb25det/engine/214/ ...but I can prattle on a bit here. These trannies have a thermistor in the sump ~ the TCU reads this and 1. bumps the line pressure up when the ATF is 'cold' and 2. prevents the TC lockup clutch from operating, until the ATF comes up to minimum operating temp (keeps the ATF 'churning' through the TC so it heats up quicker) -- trigger point is around 55C. In these conditions, the engine coolant temperature rises faster than the ATF temperature, and also helps heat the ATF up, which is why it's best to think of the in radiator tank setup as a heat exchanger ; the heat can flow in both directions... ...with these trannies, the 'hot' ATF comes out the front banjo bolt, flows through the cooler/heat exchanger, and returns to the box via the rear banjo bolt. This gets a mention, due to the wildly different opinions wrt running auto trans fluid coolers ~ do you bypass the in radiator tank altogether, or put the cooler inline with the in radiator tank system...and then, do you put the additional cooler before of after the in radiator tank system?... ....fact is the nominal engine operating temp (roughly 75C), happens to be the ideal temperature for the ATF used in these trannies as well (no surprises there), so for the in radiator tank system to actually 'cool' the ATF, the ATF temp has to be hotter than that...lets say 100C -- you've got 25C of 'excess' heat, (slowly) pumping into the 75C coolant. This part of the equation changes drastically, when you've got 100C ATF flowing through an air cooled radiator ; you can move a lot more excess heat, faster ~ it is possible to cool the ATF 'too much' as it were...(climate matters a lot)... ...in an 'ideal' setup, what you're really trying to control here, is flash heating of the ATF, primarily produced by the TC interface. In a perfect world, wrt auto trans oil cooling, you want a dedicated trans cooler with builtin thermostatic valving - they exist. These should be run inline and before the in radiator tank system ~ when 'cold' the valving bypasses the fin stack, allowing the ATF to flow direct to the in radiator tank heat exchanger, so it works 'as intended' with helping heat the ATF up. When 'hot' (iirc it was 50C threshold), the valving shuts forcing the ATF through the cooler fin stack, and onto the in radiator tank heat exchanger...and you sort of think of it as a 'thermal conditioner' of sorts...ie; if you did cool your ATF down to 65C, the coolant will add a little heat, otherwise it works as intended... ...the 'hot' ATF coming from the front bango bolt, is instantiated from the TC when in use, so all/any flash heated oil, flows to the fluid-to-air cooler first, and because of the greater heat differential, you can get rid of this heat fast. Just how big (BTU/h) this cooler needs to be to effectively dissipate this TC flash heat, is the charm...too many variables to discuss here, but I just wanted to point out the nitty-gritty of automatic trans fluid coolers ~ they're a different beastie to what most ppl think of when considering an 'oil cooler'... /3.5cents

Yeah, this is one of the most annoying things about nissan part numbers... I've got an unrelated example... Image is of the AT output shaft ~ they have the same part#, but clearly the shaft on the left is beefier design to that on the right ...the difference (essentially) is the 'lighter' shaft on the right, is for engines up to RB25DE (this includes RB20 variants) : the shaft on the left is for RB25/26DET(T)....are they interchangeable? Yes...but obviously one shaft is going to be stronger than the other...and, the lighter shaft is around USD115, but the heavier shaft closer to USD150...same part#... ...epc-data usually tells a tale ~ the amayama listing for 39100-23U60 has a note "Longest side is between 60 and 105 cm" ; no such info is there for 39100-23U70 ...and given the great disparity in price between the 2 parts, it makes me at least curious (to the point of caution) where the 'extra money' went? ...ie; these 2 parts have a cost difference that (to myself at least) isn't explained by 'plastic boot'...ie; with amayama there's AUD700 price difference ...plastic versus rubber?...I'm not seeing it like that...and 60cm ~ 105cm...??...that's a huge disparity....something hinky going on here... I'd try searching by VIN, not model... /2cents

I'd probably start with checking the output of the accessory relays (you can check control side while you're there)

Yeah, all good ...got your postal addy as well ; I'll box the stuff in the next couple of weeks, you can paypal me later..

Did some FASTing ...got the impression that the actual part# was a moot point ; seems all of these hardlines for coolant are discontinued/NLA... like, I take it you're after the hardline that bolts onto to the manifold...that's NLA according to amayama & nengun .... ...just to clear up some confusion, they typically mounted the AAC valve to the intake manifold somewhere near a coolant passage, so the body of the valve heats up & holds it open when engine's up to temp - no coolant flows through the valve, it's a mechanical, thermal connection.

Wrt the engine, you're very much limited by 'production quality' as to how much extra power you can extract from them (I'm talking i6 red-motor) -- a lot here depends on how 'authentic' or 'period correct' you want the modifications to be... ...I'm too old... <grin>...the first true performance engine Holden made, was in the HD/HR models ~ this was the 'X2' performance pack...it came with twin downdraft strombergs on an otherwise unimproved intake manifold, with a two piece exhaust manifold (reckoned to be as good as extractors)... ....these engines were built upon the '179HP' cylinder block, which included extra webbing in the casting to make it stronger and less susceptible to block distortion... The next performance i6 came out with the HK Monaro (also found it's way into the LJ GTR Torana ... the car I wish I hadn't sold)...it had pretty much the same manifold setup, but was built against the '186S' block...this block retained all the extra webbing of the 179HP block, but added a forged steel crankshaft (instead of the stock cast crankshaft), because it was possible to snap the crank... ...apart from the inherent weaknesses in the stock (cast crank) blocks, the next limiting factor is the cylinder head porting & combustion chamber design, and the actual valve sizes. Back in the day, you could buy a 'yella terra' cylinder head (from stage 1 to stage 5 gradients), and this was the way to get serious power out of them -- with the extra breathing of these heads, you could fit a triple SU or DCOE Weber setup... ...obviously, these mods were a waste of time on a stock cylinder head/camshaft grind. My housemate rebuilt the i6 in his VH dunnydore about 6 months back -- this is a 186S block with the 12port 2850 blue motor head and intake/exhaust manifolds, with a dual throat Weber off an XF Falcon mounted on an adapter plate ; it's not a bad makeup...got more torque & fuel economy just light-footing it about on the first throat, but stand on it and it makes more giddy-up than the standard 2850 blue motor that it replaced. Personal note: I'd just fit an RB30 and be done it it 😃

I PM'd you my email address 😃

Do you still need the wiper motor and stuff?

Oops... I meant to include the connector view... BR/W - power from fuse L/W - motor negative to fan control amp (and off to HVAC pin19) OR/B - PWM signal (from HVAC pin20) B -- ground

G'day ... first up, I very much doubt that's a resistor network (as used also for this job), but the part# looks right. The description of 'power module assembly' looks to be nissanese for 'PWM driven, ground switched, DC motor speed controller'.... the circuit in the schematic kinda infers that's the case... ...with the transistor symbol appearing in the unit described here as 'Fan Control Amp(lifier)'....being driven by pin20 on the HVAC unit, and a feedback signal on pin19 from the motor negative terminal for some reason (might be motor fault detection, maybe they detect commutator switching to determine motor revs as well, I dunno)... but if they are counting commutator spikes, a bad segment (or really worn brushes) will throw a spanner in the works... The motor itself will as said be brushed DC with segmented commutator, rated at 12VDC nominally ~ now-a-days I just unplug them, determine the positive wire, and hook them up to a variable power supply and find out how much current they draw, if they work etc etc ...you can also check for bad segments...ie; set the power supply up to feed 1volt @ 2amp max, then watch the wattage count as you slowly rotate the fan blower motor through a complete revolution ; any bad/dead segments will be clearly evident...some folks would just say determine the positive wire, and feed it battery voltage, and if fan spin, you've got a win...<grin>... well, at least that infers it should do something when plugged back in, and the HVAC unit commands it to run... and if it doesn't, you suspect the module, but you should check the PWM signal on pin20 is actually present, and if it is, blame the module ...

Ahh...should have been clearer ~ there's 2 ... SMJ = super multi junction (connector)... ...this is connector 6 & 25 in above image -- body harness to engine loom (6) & body harness to main loom (25) Headlights go to front via connector 6 ; fuel gauge goes to tank sender via connector 25 ...like I say this is R33 diagrams, but at a pinch R34 won't be too far different. *IF* the two ground faults are related, this can be the only place where both wires converge (as one runs to the back, the other to the front)... ....thing is, you probably need to establish if the faults are related (unless you examine that area and find obvious chaffing on the looms there to body ground)....*IF* the fuel gauge is still broken (full needle deflection), I'd be headed for the boot, remove fuel sender wire, key on and measure the voltage there ~ it should be roughly 10volts. If that's ok, check sender to ground resistance...if this is a dead short to ground (and there's fuel in it), then sender has failed or something funky has happened to wiring in the tank. edit: ahh...rereading the thread, this is R32....above fuel sender test still valid tho'

Correct ~ fuel gauge receives power (usually about 10volts) from a linear regulator on the cluster board (gives a stable reference voltage), and as you say, via a variable resistor to ground (float level) ; high resistance when tank empty, a low resistance when tank full. As you surmise, if the fuel sender wire was shorted to ground, there'll be full defection of the fuel gauge needle. I haven't got an R34 wiring diagram, but going by the R33 spaghetti schematic, about the only thing common here between headlight & fuel gauge circuits is the SMJ connector...

Yeah, R34 with RB25DE likely has a 4AX01 box in it, which is a medium duty auto ~ with the RB25DET mill, it would've been fitted with 4AX00 (4AX13) heavy duty build (same case, different internals). An RB25DET will lunch on a medium duty 4R01 auto in pretty short order ...to give you some visual idea of differences between the 'medium' and 'heavy duty' boxes, you only have to look at the 2/4 band for comparison...it's chalk and cheese...(plus bigger high clutch, extra pinion in the planetary sets, higher oil pump output, different bearings, higher TC stall speed )... You can control them with just about any aftermarket TCU for electric-over 4-speed with TC lockup clutch (ie; the GM 4L60E and others)...I have a custom standalone TCU that includes MAP sensor (for turbo applications) along with TPS, RPM, and line pressure monitoring...in other words, I don't use any ECU signals...no real need to.

Very unlikely...

He's right ~ there is no 'magic' with stuff like this ... it is more likely that in the process of looking for the short, the loom/wire 'incidentally' got moved in the process, thus removing the short ~ now, that maybe a wire (in a loom) rubbing against the edge of some grounded metal, that's worn through the insulation, causing the (now intermittent) short to ground. If one wire in a loom has been damaged in this fashion, it's reasonable to presume that other wires beside it may have also be damaged, and now exposed...you can bet the green crusty copper corrosion will start... ...that'd be a pisser, Murphy's Law steps right in as GTS observes...but worse, something like that is easier to find when shorted...ie; unplug bulb and fuse, and put multimeter in continuity mode so you get constant beep, and carefully poke about hoping to find if some movemet of the harness stop the beeping.... ...it's still all a bit Arnie tho' ..It'll be back... 😃

...yep, in the dark of a wet rainy night most likely 😃

Yeah. air pressure leakdown test is where I would be headed next here, using one's ears to determine whether it's the valves or bores/rings leaking...