total electrical failure | Joined: Jul 2016 Posts: 19 stranger | OP stranger Joined: Jul 2016 Posts: 19 | hello... just had a complete electrical failure in my 75 g20. i have absolutely nothing working..but have 12.57 volts at battery pos & neg terminals, at the batt cable to the starter, at the batt wire terminal on the start switch connector and at the batt pos terminal and any frame or body ground. found an intermittently open batt neg cable from the engine to the neg post. replaced with new cable, it rang out fine for continuity before installation and after. i've metered out the start switch for continuity and have good readings at all terminals at the right times corresponding to key position. fuses are all good, no frame chaffing on the batt cable to the starter, connections are all tight and corrosion free.
with the switch in off, i get no headlights or hazard lights. with it in acc or on i get no headlights, blower fan, wipers signals and the gages dont come alive. in start nothing happens; no starter solenoid click. i tried jumping from batt to solenoid at the start switch connector, no luck. fusible link appears good at the starter.
i dropped a servicable battery in it less than 2 weeks ago, used, but load tested fine. it's started and run fine since and did so this morning when i drove it to work. it failed to start after work the first time turned the key but started normally the second time. im not seeing any needle deviation, either charge or discharge on the batt gage when its running, but it did meter out at 14.3 vdc at the battery when i ops checked the battery after install.
i fix airplanes for a living; dc power systems arent foreign to me, but this has me scratchin my watch & windin my head. im leaning toward a battery amp issue.... voltage, but no amps. my meter doesnt have a load cell function..... any thoughts?
thanks!! | | | Re: total electrical failure | Joined: Dec 2013 Posts: 415 Likes: 2 addict | addict Joined: Dec 2013 Posts: 415 Likes: 2 | I would look at the starter solenoid and the ignition switch. | | | Re: total electrical failure | Joined: Jul 2016 Posts: 19 stranger | OP stranger Joined: Jul 2016 Posts: 19 | starter switch checks out good with a meter for continuity between all the pins whan the key is turned. i've got 12 volts in at the battery wire at the starter switch connector and good continuity to ground from both the ign and sol wires on the connector. im pretty certain my switch is ok. ive got power to the solenoid at both the coil terminal and the battery cable. what i dont have is anything working. it seems like theres an open at tge fusible link, but that wouldnt allow me to have power at the starter switch...... | | | Re: total electrical failure | Joined: Feb 2007 Posts: 194 member | member Joined: Feb 2007 Posts: 194 | A tip, use a test light to do your voltage checks. It will provide a small load. If the fuse link is blown you could still measure voltage with a very good volt meter. Private pilot A&P and Exp. Home builder.
Political correctness is a doctrine fostered by a delusional, illogical minority, and rapidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by a CLEAN end. | | | Re: total electrical failure | Joined: Jul 2016 Posts: 19 stranger | OP stranger Joined: Jul 2016 Posts: 19 | thats my take as well, but im not showing open at the link. pinned out both ends. it may be partially gone and showing continuity and carrying a small voltage path, but not enough to hold an amp load. its in the worst place you could put it. (when i become president, all engineers will have to do at least 5 years as a mechanic before theyre allowed to be an engineer and design anything, especially aircraft engineers.....) surprisingly, nothing appears corroded anywhere..... whats really got me torqued is it went from starts right now to absolutely dead in about 15 minutes. i suspect the ammeter is inop & the alternator's ok based on the 14 vdc i got at the battery with it running. links are cheap so ill throw one at it and a known good battery this morning... to be continued...... | | | Re: total electrical failure | Joined: Feb 2007 Posts: 194 member | member Joined: Feb 2007 Posts: 194 | If you can get at the link, give it a good tug. a bad link will usually pull apart.
Political correctness is a doctrine fostered by a delusional, illogical minority, and rapidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by a CLEAN end. | | | Re: total electrical failure | Joined: Jul 2016 Posts: 19 stranger | OP stranger Joined: Jul 2016 Posts: 19 | battery chevked and load tested fine.... there are 3 fusible links per the wiring diagram...2 at the starter solenoid and one at a busbar somewhere on the firewall. the quest has begun in the search for the holy link......just to make it fun, the previous owner thought it would be a great idea to rattlecan paint the engine bay red. a hideous, hooker nail polish red. even all the wires......did i mention he did the interior the same way? without pulling or masking anything? | | | Re: total electrical failure | Joined: Jul 2016 Posts: 19 stranger | OP stranger Joined: Jul 2016 Posts: 19 | victory is mine......in the interest of adding to the general knowledge and to highlight my own overthinking, i submit the following for consideration:
at some point, the previous owner replaced the starter. he did not, however, replace the YUUUUUGGGGE ring terminal on the cojoined 14 gauge and 20 gauge fusible links at the solenoid so it actually fit the obviously smaller diameter than original positive battery stud. nor did he use proper torqueing procedures to tighten the nuts which hold said ring terminals securely on said studs. nor did he bother with the two cent lockwasher which would have kept them that way. there was just enough contact to carry battery voltage throughout the entire wiring harnesses to register on my fluke meter, and enough to show continuity, but not enough to carry any amperage whatsoever.
long story short, the power cable and fusible links were loose on the solenoid positive stud. driving it backed the nut off just far enough to break solid contact thus killing the entire power system, but not causing a complete open. there were some other minor wire routing issues and just shoddy stuff that gave my aircraft mechanic brain the vapors, but they werent contributing factors...
tips.....lockwashers are your friends.. and snug isnt good enough.
| | |
0 members (),
31
guests, and
7
robots. | Key: Admin,
Global Mod,
Mod | | Forums68 Topics35,844 Posts538,421 Members12,736 | Most Online177 May 8th, 2013 | | | |