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== gpt-5-2-thinking == === User: Read over this manual. === Read over this manual. I need to know how to change out the power distribution box that sits on top of the battery in my 2007 BMW 328i e90 n52 engine. I also need to know how to use my pb6000 to test the battery and starter and alternator for my car, since my car has a freshly charged battery that when connected my car and attempted to start it. The car cranks really fast, but won’t catch and start. The amps being put out by the battery during cranking is 11.4. I think it has to do with the power distribution box, which mine is melted and warped and flimsy or the front of the car positive jump post and chassis ground or the alternator. Also, I bought the Autool E365 150 A programmable battery charger and maintainer. Then I have ISTA+ and ISTA-P with a K+ D-Can cable. I also have INPA, so if you can guide me through how to use these programs and devices for what I need done to my BMW. But I am need a step by step guide on how to change the power distribution box. So I can get the correct cranking voltage out of my car. === Assistant: Here’s the straight story: on an E90, you can absolutely get a “cranks fast but won’t start” situation if the rear powe… === Here’s the straight story: on an E90, you can absolutely get a “cranks fast but won’t start” situation if the rear power distribution panel on top of the battery (A46) is heat-damaged internally—because it doesn’t just feed the starter cable. It also feeds engine electronics (DME/Valvetronic) on a separate path. The manual even calls out two different power feeds leaving the battery area—one to the jump post/starter/alternator and another to engine electronics. 461232-BMW_3-Series_E90-E91_200… 461232-BMW_3-Series_E90-E91_200… ==== BMW calls it the Rear power distribution panel (high amperage fuses) (A46) and it sits directly on top of the battery in the trunk. 461232-BMW_3-Series_E90-E91_200… ==== Those “big fuses” inside it are fusible links and are not replaceable separately—so if the panel is melted/warped, replacement as an assembly is the right move. 461232-BMW_3-Series_E90-E91_200… It has outputs/lines going to: starter/alternator/jump post, engine electronics, IBS electronics, and the junction box. 461232-BMW_3-Series_E90-E91_200… ==== I’m going to call this out because it matters: ==== * If you meant 11.4 VOLTS while cranking, that’s actually strong (most cars dip closer to ~9.6–10.5V during crank, depending on temperature/load). So your problem may be not battery strength but fuel/spark/DME power/immobilizer. * If you meant 11.4 AMPS, that’s not a realistic cranking number—starters pull hundreds of amps. That would mean the reading is being interpreted wrong or measured in the wrong mode. The PB6000 tests below will clear that fog fast. ==== This is the exact removal flow the manual gives, and it’s the safest way to access A46. 461232-BMW_3-Series_E90-E91_200… ==== ===== - 10mm socket/wrench (battery terminals) ===== * Ratchet + extensions * Torque wrench (important) * Gloves/eye protection * Phone to take “before” photos (do it—future you will thank you) ===== 1. Ignition OFF. 461232-BMW_3-Series_E90-E91_200… ===== # In trunk, open the battery compartment. Remove right-side trim (plastic retainer). 461232-BMW_3-Series_E90-E91_200… # Remove the protective bracket over the battery (mounting fasteners) and lift it off. 461232-BMW_3-Series_E90-E91_200… # At the battery, disconnect negative FIRST (loosen fastener “A”). 461232-BMW_3-Series_E90-E91_200… - Be gentle: the IBS is attached to the ground cable and is stress-sensitive. The manual is loud about not pulling, prying, or levering on the IBS/ground cable. 461232-BMW_3-Series_E90-E91_200… # Unlock the BST plastic cover, loosen the positive cable fastener “B.” 461232-BMW_3-Series_E90-E91_200… # Carefully lift the rear power distribution panel (A46), positive cable, negative cable, and IBS off the battery and lay aside. 461232-BMW_3-Series_E90-E91_200… # Remove battery hold-down bolt “C,” disconnect the vent hose, lift the battery out. 461232-BMW_3-Series_E90-E91_200… ===== Bentley shows you how to lift A46 off as an assembly. Once it’s off and on a bench: ===== # Photograph everything: every cable routing, every nut, every connector position. # Transfer cables/connectors from the old A46 to the new A46 one at a time (so nothing gets swapped). - Remember: A46 includes the high-amperage fusible links—they aren’t serviced separately. 461232-BMW_3-Series_E90-E91_200… # Inspect the mating points for heat damage (discoloration, pitting, looseness). Any heat at a high-current joint = resistance = voltage drop = future meltdown. ===== - Reconnect negative LAST when reinstalling the battery. 461232-BMW_3-Series_E90-E91_200… ===== * Battery post pinch-bolt torque specs: - M6 = 5 Nm (44 in-lb) - M8 = 15 Nm (11 ft-lb) 461232-BMW_3-Series_E90-E91_200… * After battery reconnect, if the battery was replaced/changed in rating: the car may need CAS recoding + battery registration. 461232-BMW_3-Series_E90-E91_200… ==== Most PB-style testers follow this same logic. If your menu wording differs, the flow is still identical. ==== ===== 1. Clamp PB6000 leads directly to the battery posts (not the cable ends), or to the underhood jump post + a solid engine ground. ===== # Select Battery Test → In Vehicle # Choose battery type (Flooded / AGM / etc.) # Enter the battery rating shown on the label (usually CCA). # Run test and note: - Voltage - State of Health (SOH) - Internal resistance - “Good / Recharge / Replace” verdict What you’re looking for: a battery can show “charged” but still be weak under load (high internal resistance). The tester catches that. ===== 1. Select Cranking Test / Starting Test ===== # Crank the engine (even if it won’t start). # Record minimum voltage during crank. Interpretation cheat code: * Low min voltage and “slow crank” → weak battery / bad starter / engine drag * Low min voltage and “fast crank” → usually measurement point issue or bad connection/voltage drop * Healthy min voltage (your claimed 11.4V) and no start → stop blaming the battery and chase DME power, fuel, spark, CAS start authorization ===== Once it starts and idles: ===== * PB6000 Alternator Test at idle and with loads on. * Bentley’s charging quick-check numbers: ~12.6V key off and 13.5–14.5V running; and with loads at ~2000 rpm it should stay above 12.6V. 461232-BMW_3-Series_E90-E91_200… ==== This is the fastest “truth serum” for high-current problems. ==== ===== - Put multimeter red lead on battery + post (in trunk). ===== * Put multimeter black lead on underhood jump post. * Crank engine. * Reading should be very low (ideally under ~0.2V). Higher = resistance in A46/cable/junctions. ===== - Red lead on battery – post. ===== * Black lead on a bare metal point on engine block. * Crank engine. * Should also be low (ideally under ~0.2V). Higher = bad ground path (chassis ground, engine ground strap, IBS connection issues). If either test is high, that’s where your “melted, warped, flimsy” story turns into a measurable cause. ==== Bentley stresses that clean, consistent voltage matters—especially when coding/programming—and recommends a power supply style approach. 461232-BMW_3-Series_E90-E91_200… ==== * Connect charger/power supply to engine compartment B+ and ground (jump post + ground), and follow the charger’s voltage setting instructions. 461232-BMW_3-Series_E90-E91_200… * Bentley mentions BMW’s charging voltage recommendation 14.8V and warns don’t exceed 16.5V. 461232-BMW_3-Series_E90-E91_200… 461232-BMW_3-Series_E90-E91_200… For diagnostics (ISTA/INPA), set the charger to a stable supply mode if it has one (commonly ~13.6–14.4V). For programming (ISTA-P), you want maximum stability—no bargain “dumb charger” behavior. ==== Your symptom screams: either DME isn’t powered/awake or it’s awake but you’re missing fuel/spark or start authorization. ==== ===== 1. Put the charger on the jump post + ground (stable voltage). ===== # Plug in K+DCAN, ignition ON (cluster lit). # Open ISTA → Operations → Read out vehicle data → Complete identification # Run Vehicle Test. # Look at the control unit tree: - If DME is not responding, that’s a giant arrow toward A46 / fusible link / DME power feed (because the starter can still crank on its own feed). # Pull fault memory for DME + CAS. # Run the guided test plan for engine does not start (ISTA will walk you through rpm while cranking, start enable, etc.). ===== 1. Open INPA, choose E90 chassis. ===== # Go into CAS: - Look for start enable / terminal 50 request / key recognized style statuses. # Go into DME (MSV/MSD for N52): - Confirm you can communicate - Watch live data while cranking: RPM signal (if 0 rpm, crank sensor/rpm input problem) - Check any “start conditions not met” flags ===== ISTA-P is for programming/coding. Don’t bring it out until: ===== * the car starts reliably, and * you have stable power supply voltage (programming on shaky voltage is how modules get bricked). ==== 1. Replace the melted A46 (your panel is already physically telling on itself). Use the Bentley battery removal steps above. 461232-BMW_3-Series_E90-E91_200… ==== # Do voltage-drop Test 1 and Test 2 during cranking (before and after). # Run ISTA Vehicle Test and see if DME is alive. # If DME is alive: chase fuel/spark/start authorization instead of charging parts blindly. If you want, tell me one detail and I’ll tailor the no-start path precisely: When you crank, does the tach needle move even a little? (That single sign often separates “DME has rpm signal” from “no rpm signal,” and it changes the whole hunt.) === User: I meant 11.4 volts when cranking === I meant 11.4 volts when cranking === Assistant: Got it — 11.4 volts while cranking. === Got it — 11.4 volts while cranking. That’s actually a healthy cranking voltage. It means the battery + starter circuit is not collapsing under load. In plain terms: the starter is spinning, the battery is holding, and the “big power” side is doing its job. So if it cranks fast but won’t catch, the problem is usually not “insufficient cranking voltage.” It’s almost always one of these: * No fuel (fuel pressure, pump control, injector pulse) * No spark * No RPM signal (crank sensor / DME not seeing engine speed) * Start not authorized (CAS/EWS logic) * DME not powered / not awake (this can still relate to that melted distribution panel, because it has multiple feeds) ===== Even if the starter cranks fine, the rear distribution panel can have a separate feed that powers engine electronics. So you can get a “strong crank / no start” if starter feed is fine but DME feed is not. ===== ==== ### ==== This is the fork in the road. ISTA+ # Put your charger on jump post + ground (stable voltage). # Ignition ON. # ISTA → Read out vehicle data → Vehicle test # Look at the control unit list: - If DME does NOT respond / not present → power feed / fuse link / distribution panel / wiring issue is very likely. - If DME responds → stop chasing voltage and go after fuel/spark/authorization. INPA * Go into DME: confirm you can communicate. * Go into CAS: look for start enable / key recognized. ===== Pick the easiest ones you can do safely. ===== Fuel * When you key ON (not crank), do you hear the pump prime briefly? * If you have a scan tool that shows it: check fuel rail pressure actual while cranking. * If pressure is low/zero → fuel delivery problem. Spark * If you can safely test: spark test on one coil (proper spark tester preferred). No spark → ignition/DME/start enable path. ===== Even though 11.4V is good, a melted panel can still create weird “split-power” issues. ===== Use a multimeter while cranking: Test A: Battery + post → underhood jump post * Red lead: battery positive post (in trunk) * Black lead: jump post * Crank * You want very low drop (roughly under ~0.2V). If you see something like 0.5V, 1.0V, etc. → resistance in the distribution panel/cable/junction. Test B: Battery – post → engine block * Red lead: battery negative post * Black lead: bare metal engine block * Crank * Same idea: low drop good; high drop = bad ground path / ground strap / IBS connection area. These tests don’t guess. They convict. ===== - Battery test: good for health/internal resistance. ===== * Cranking test: you already basically did; 11.4V min is strong. * Charging test: only meaningful once it starts and runs. So right now, the PB6000 is mostly telling you: “battery isn’t the villain.” ==== If it’s melted/warped/flimsy, replacing it is still smart — melted high-current joints are a future fire + failure waiting to happen. But don’t expect that alone to magically fix a no-start unless we confirm the DME power path is compromised. ==== ==== Answer these and I’ll give you the exact next test steps (ISTA/INPA screens + what values to look for): ==== # Does the tach needle move at all while cranking? - If it stays dead at 0, that points hard at crankshaft position signal / DME seeing RPM. # In ISTA, during the vehicle test, does DME communicate (yes/no)? If you answer just those two, I’ll map the next moves step-by-step—no wandering, no parts cannon. === User: Sorry I meant the battery shows 11.4 V at ignition on but care not started === Sorry I meant the battery shows 11.4 V at ignition on but care not started === Assistant: All good — and that detail changes the whole picture. === All good — and that detail changes the whole picture. 11.4 V with ignition ON (engine not running) is low. Not “a little low”… low enough that BMW modules can get weird, the CAS/DME can throw a fit, and cranking performance (and especially spark/fuel control) can become inconsistent. ===== If you’re measuring at the battery posts (not the cable ends): ===== * 12.6–12.8 V = healthy, fully charged (typical) * 12.2 V = about half charged * 11.8 V and below = basically drained/weak * 11.4 V = either deeply discharged OR the battery is bad OR you’re losing voltage through a bad connection So before we blame the alternator (can’t test it until the car runs) or even the power distribution box, we’ve got to prove where the voltage is being lost. ==== Get a multimeter and take these readings with the car sitting (ignition OFF first), then ignition ON. ==== ===== - Ignition OFF voltage = ______ ===== * Ignition ON voltage = ______ ===== - Ignition OFF voltage = ______ ===== * Ignition ON voltage = ______ Interpretation: * If battery posts show 12.4+ but jump post shows way less → distribution box / main cable / connection issue * If both show 11.4-ish → battery is discharged/weak or there’s a heavy draw happening immediately with ignition ON ==== 1. Hook the charger to the underhood jump post + ground (or directly to the battery posts in the trunk if you prefer). ==== # Charge the battery fully. # After charge completes, let it rest 30–60 minutes (surface charge fades). # Re-check voltage at battery posts. If it won’t come up into the 12’s, the battery is either failing or there’s a parasitic draw dragging it down fast. : ==== ### ==== * Select battery type (AGM vs flooded) * Enter the CCA rating from the battery label * Run test If it says “Recharge & Retest” — do exactly that. Testing a discharged battery gives misleading results. ===== - Run the cranking test and watch minimum voltage while cranking - If it drops below ~9.6 V: battery weak / starter draw too high / bad cables - If it stays strong but won’t start: now we chase fuel/spark/start enable ===== ===== Ignore alternator testing until the engine actually runs. ===== ==== This is where your melted power distribution box and connection points become prime suspects. ==== ===== - Battery terminals tight and clean (no rotation by hand) ===== * IBS on the negative cable not cracked/loose * Rear distribution panel (melted/warped) = replace it — heat damage = internal resistance * Underhood jump post: nut tight, not corroded * Chassis ground points: clean, tight * Engine ground strap: intact (common silent killer) ===== If you want one test that cuts through the noise: ===== Positive side drop * Red lead on battery positive post * Black lead on jump post * Ignition ON / crank * You want a small number. Big number = resistance in distribution box/cable. Ground side drop * Red lead on battery negative post * Black lead on engine block * Ignition ON / crank * Big number = bad ground path/strap/connection. ==== Low voltage can cause false symptoms. So do this after you get solid voltage. ==== ===== - Run a full vehicle test. ===== * The key question: Does the DME (engine computer) communicate? - If NO → power feed/fusing/distribution box/wiring is very likely. - If YES → go to live data while cranking: - Engine RPM present? - Start enable? - Injection and spark plausibility faults? ===== - Check CAS for start authorization ===== * Check DME for RPM while cranking and fault codes ==== Right now, 11.4 V key-on is a warning flare: either the battery is not truly healthy/charged, or you’ve got voltage loss through that melted distribution panel / cables / grounds. ==== If you tell me just two numbers, I’ll point you to the exact culprit: # Voltage at battery posts with ignition ON # Voltage at jump post with ignition ON And tell me one more thing: when you try to start, does it crank, or is it click/no crank? === User: It’s a very fast crank with === It’s a very fast crank with === Assistant: A very fast crank with no start usually means one of two things: === A very fast crank with no start usually means one of two things: # The engine is not actually being turned by the starter (starter is “whirring”/free-spinning), or # The engine is turning, but it has no combustion (no fuel / no spark / no RPM signal / no start authorization) — and “fast” is just how it sounds when it isn’t firing. With your earlier detail (~11.4 V with ignition ON), low system voltage can also make BMW modules act drunk, but it usually causes slow crank more than “fast crank.” So we need to separate sound from facts with two quick checks. ==== Do this first — it changes everything. ==== * Have someone crank the car while you watch the serpentine belt / crank pulley up front. - If the belt/pulley does NOT move: the starter may be spinning but not engaging (or mechanical issue at the ring gear). That’s “fast crank sound” but the engine isn’t turning. - If it DOES move: the engine is turning. Go to Step 2. (If you’re solo: prop your phone to record the belt area while you crank for 2 seconds.) ==== If you truly have 11.4 V key-on, clip your Autool E365 to the jump post + ground and keep it on supply/charge while testing. ==== Then check voltage with a multimeter: * Battery posts (trunk), ignition ON: you want 12.0+ * Jump post (hood), ignition ON: should be basically the same as battery If there’s a big difference between trunk posts and jump post, that points right back to distribution panel / cable / connections. ==== ### ==== * ISTA+ → Vehicle Test - If DME is missing / not responding → strong evidence of DME power feed / fuse link / distribution panel trouble (even if the starter still cranks). - If DME communicates → stop blaming power distribution as the primary no-start cause and move to live data. ===== - In INPA → DME → Live data, crank the engine and look for engine speed (RPM). - 0 RPM while cranking: crankshaft position signal issue (sensor/wiring) or DME not truly awake. - RPM present (150–300ish): crank sensor signal is likely OK → now it’s fuel/spark/start enable. ===== ===== - INPA → CAS: check start authorization / key recognized. - If start isn’t authorized, it’ll crank in some failure modes but won’t inject/spark normally. ===== ==== If the engine is turning and DME sees RPM: ==== * Fuel check: after cranking attempts, do you smell raw fuel at the tailpipe? Are the plugs wet? * Spark check: if you have a spark tester, check one coil for spark while cranking. No fuel + no spark together often points to start authorization/DME control, not a pump. ==== If what you’re hearing is a smooth, “zip-zip-zip” that’s noticeably faster than normal and almost too easy, that can mean low compression across multiple cylinders (rare, but real). ==== Fast triage: * Watch the belt (Step 1). If it turns, do a compression test (or at least a quick compression gauge check on 2 cylinders) before you spend money elsewhere. ===== Reply with just this one result: ===== When you crank it, does the serpentine belt/crank pulley move? (Yes/No) And if yes: tell me whether INPA/ISTA can talk to the DME and whether RPM shows while cranking. With those three answers, I can give you a clean, step-by-step “do this, then this” path to the exact cause — no parts cannon. === User: Give me step-by-step instructions according to the manual, I uploaded you on how to change the rear power distribution … === Give me step-by-step instructions according to the manual, I uploaded you on how to change the rear power distribution box === Assistant: Below is the manual-based, step-by-step procedure for removing the battery and lifting off the rear power distribution … === Below is the manual-based, step-by-step procedure for removing the battery and lifting off the rear power distribution panel (A46) so you can replace it, exactly in the sequence Bentley lays out. ==== ### ==== # Ignition OFF. 461232-BMW_3-Series_E90-E91_200… # Open the trunk battery compartment and remove the right-side trim panel (plastic retainer). 461232-BMW_3-Series_E90-E91_200… # Remove the protective bracket over the battery (remove mounting fasteners) and lift it off. 461232-BMW_3-Series_E90-E91_200… ===== 1. At the battery, disconnect the negative (–) cable first by loosening fastener “A.” 461232-BMW_3-Series_E90-E91_200… - Important caution: the IBS (intelligent battery sensor) is on the negative cable. Do not pull, pry, or lever on the IBS/ground cable assembly. 461232-BMW_3-Series_E90-E91_200… ===== # Unlock/open the BST plastic cover, then loosen the positive (+) cable fastener “B.” 461232-BMW_3-Series_E90-E91_200… # Carefully lift off the rear power distribution panel (A46) together with the positive cable, negative cable, and IBS, and set it aside. 461232-BMW_3-Series_E90-E91_200… # Remove the battery hold-down bolt “C.” Disconnect the battery vent hose. Lift the battery out. 461232-BMW_3-Series_E90-E91_200… ===== 1. With A46 off the battery, transfer each cable/connection from the old panel to the new panel one-by-one (so nothing gets mixed up). - Bentley notes the high-amperage fuses in this panel are fusible links and aren’t replaceable separately, which is why a melted/warped unit typically gets replaced as an assembly. 461232-BMW_3-Series_E90-E91_200… ===== # Inspect every ring terminal and stud for heat damage/discoloration. Any burnt/blue/pitted connection should be corrected now, or it’ll cook the new panel. ===== 1. Reinstall the battery (vent tube connected, hold-down installed). ===== # Reinstall the A46 panel and cables back onto the battery. # Reconnect positive (+) first, then negative (–) last. 461232-BMW_3-Series_E90-E91_200… # Torque the battery terminal clamp bolts to spec: * M6 terminal bolts: 5 Nm (44 in-lb) * M8 terminal bolts: 15 Nm (11 ft-lb) 461232-BMW_3-Series_E90-E91_200… # Reinstall the protective bracket and the trim panel you removed earlier. 461232-BMW_3-Series_E90-E91_200… ===== 1. If the battery was replaced or its rating/type changed, Bentley notes you may need CAS recoding + battery registration. 461232-BMW_3-Series_E90-E91_200… ===== If you tell me whether your battery is in the trunk on the right side (most E90s) and whether your new A46 has the same number of studs/outputs as the old one, I’ll also give you a clean “transfer map” checklist so you can move each cable in a no-mistakes order.
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