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RJK

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  1. Occams razor reared its' head on this one, I think. The problem was the battery....I replaced it with a new battery, and the car cranks fast and strong. When I saw the voltage reading, I assumed it was sufficient, but it doesnt look like it could move enough amperage fast enough to turn the engine over. Thanks so much for your help folks!
  2. Welp, I don't know what I'm doing wrong here, but I obviously have something wired improperly. When I try to fire the car, I get no cranks, and all lights go blank. With the key at the accessory position, lights come on, and I hear the fuel pump run. Everything goes immediately dark if I try to start. Here's my specs: -all fuses have continuity -new starter motor -proper motorsport auto 6 pin adapter for internally regulated alternator -battery on trickle charger for 3 days straight; reads over 13V once removed from charger I'm sorry to be the problem child here; really stumped here. Any help appreciated.
  3. Thanks Steve. I literally read this post 5 times, so I am doing my darnedest to deduce the alternator labeling. I'm trying, I swear! This helps me understand what the L and S terms mean, relative to the internal wiring of the car. That part I have a solid grasp on. It's translating these terms to the language used on the ZCarDepot site's literature for the alternator that I am attempting to confirm. From your language, I gather that the ZCarDepot labeling one pin "Ignition Key On" should tie to the L wire, internal to the car, correct? Since the ignition key would be switching on and off, and, the L wire is a switched source, right? And what the ZCarDepot labels "to 12V post" would be the S wire, since to quote your post, the S senses the battery voltage, correct?
  4. Thanks Steve. I can diagnose the wiring as you described. The last thing I need confirmation on is the terminology used on the labeling of the alternator itself. Is the S or "sense" terminal of the alternator going to be the labeled "ignition key on", and L terminal labeled "12V post"? Or do I have that inverted?
  5. Hey folks, sorry to beat a head horse, but I want to double check my wiring at the stock T harness at the alternator. On the attached image, would the "ignition key on" terminal be considered the S terminal, and "to 12V post" be the L terminal? Also, just to clarify, the "cross" of the T would be the "top bar" of the T, with the vertical on the T being, well, the vertical pin, with the connector oriented as a capital T? I know this all is pretty elementary, but I need to double check my work. I attempted a start, and got 2-3 cranks, and then right to clicking. My battery read about 12.5V, but on my old alternator/starter rig, the car would slow the cranks down; I never got clicking at the ignition if the battery was low. Thanks for the help. So, if wired properly, my harness would look like this image? the harness is oriented as the plug on the alternator is, with the green wire being the "top"(S/ignition key on?) pin, and the red wire being the bottom (L/12V post?) pin?
  6. I appreciate all your help, guys. I am honestly fine spending the time on this, if the end result is A)I'm confident in my wiring, and b) I learn some things about diagnosing electrical issues. Thanks!
  7. Well, as many I think have suspected, this looks to be filed under "user error". I closed the PS door, rechecked all switches at the steering column(headlights, turn signals, etc etc). Rechecked, and I'm now reading about 23 ohms. Well, better safe than sorry, I guess. I think the experience of watching the insulation burn off a wire in real time kinda traumatized me. I'm gonna button everything back up, save for the alternator, and make sure I'm seeing 12V at the proper wire, and then call it a day. Thanks for all the help, folks!!!
  8. thanks guys! i checked that all my switches were off at the steering column, however, i'll do a triple check today. i'll also activate said switches with the doors closed, and watch my readings. the PS door and hood have been open on all of these readings. i would love nothing more than to find out that the readings are due to user error! as to a short at the alternator, the two alternator wires are separated in the wiring loom, and i can visibly see that the wires have integrity and cannot physically short TO anything.
  9. Ok, here's what I got from today....more baselines: starter motor sense wire is disconnected, as is alternator and fusible link. White and white/red wire connectors as PS footwell fender side are disconnected. White/red wire at center console, "pre fuse box", also disconnected. I am tying off ground pin of my DVM to an engine bay screw location. 1-tested both white wire, and white/red wire sections from engine bay to PS footwell location #1. No short; both read OL. 2-section of white/red wire from fender side to center console side: no short, OL. 3-where the 3rd section of white/red wire connects directly to fuse box, the right side of the 4th fuse down on right row, DOES show a short. See attached pics; this reads 2.7ohms. I see the junction in this wire; it looks to split off and go upwards(ammeter or ignition switch?). 4-left side of the same fuse does NOT show a short; OL on DVM. What's next? Thanks again for the help!!!
  10. SteveJ-AMAZING info here. very clear. thank you SO much. it's complicated stuff; I had to read your entire paragraph 2-3 times before I could visualize what you were describing, but now I think I can. In essence, it seems as though the white wire and white/red wire run thru a network, that includes the fuse box, ignition switch, and ammeter when they travel into the cabin. by disconnecting the molex connectors, and the connections in the engine bay, I am breaking apart that network. now, by testing at the connecting points, i can see where the network is grounding out(or close to it). very clearly put. I'll implement this procedure today, and report back.
  11. More info: 1-disconnecting this single pin, white>white red connector at the PS footwell ALSO drops impedance to OL. 2-impedance from red/white alternator wire to ground is 2.6 ohms. 3-removing 4th fuse down on right side has no effect on the ~3ohm reading I get from fusible link wire to ground.
  12. Ok, more diagnostics, and pics. I found the molex connector in the PS footwell that links to the fusible link wire. In the pics, see a 4 pin connector; when I pull it, my impedance goes OL. Obviously, I need to figure out where this traces to, but this is progress.
  13. alternator is disconnected until i know i'm not sucking current or creating a fire somewhere. so not connected on reading. 1972 240z, only upgrade is MSD ignition, wiring appears to be stock.
  14. Thanks Steve-yes, I was measuring the same test points it looks as though you were measuring. To clarify, at the fusible link that connects the starter to the car wiring(single pin molex style connector), I disconnected the fusible link, and measured with positive probe at the CAR'S wiring harness side of that connection(in your image, it would be the old and faded side of the connection), and the ground probe at numerous chassis points. With the battery disconnected, I am averaging around 3 ohms.
  15. Ok, so I just tested: Remove the fusible link and use a voltmeter and measure from the wire coming off the solenoid (for the fusible link) to the positive battery cable. If there is not a short, that should read 0V--- I DO NOT HAVE THE BATTERY LIVE, SO I DIDNT READ THIS IN VOLTAGE. IN OHMS, IT'S OVER 1K. Measure resistance between the wire coming off the solenoid (for the fusible link) to ground. If it reads less than 10 ohms, you have a significant load or short. If you have less than 1000 ohms, you will have a pretty good battery drain. -THIS READS AT 2.6OHMS TO 3.1 OHMS, DEPENDING ON WHICH CHASSIS LOCATION I USE. BUT CONSISTENTLY IS AROUND 3 OHMS. Use a 12VDC test light between the wire coming off the solenoid (for the fusible link) to the positive battery cable. If it lights up, you have a short. (Be sure to test the test light across the battery terminals to make sure you have a good bulb.)--DONT HAVE ONE OF THESE YET. So I think it's safe to say I have a short somewhere, or a load? Should my next area of focus be at or near the ignition switch? (PS-forgot to mention that for now, as a baseline, I am working with battery disconnected, alternator disconnected, and fusible link also disconnected. 6 pin VR harness adapter is seated)
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