Bench Wrenchin...what am I missing before I resort to beating me head into wall?
First some background, I do not claim to know everything electrical, that said I know the theory of electricity and how it works and how to make it work (most times...in theory). in other words I'm dangerous....gimme a mig or plasma over a pile o wire.
That said I'm completing my rewire of my 1949 chevy, wrenched on it till a few moments ago trying to get it done for the show on sat. here's what I've done,
New EZ wire harness, new VDO guages with respective sending units (all electronic), new headlights, new headlight switch, new ignition switch, new tail lights, new turnsignals (when I say new I mean bucket and all) New Ididit non keyed column, new ground straps (one from trans/Eng. block to frame, other from trans/engine block to body).
followed the directions to a T as well as followed the directions to a few questions I had from Doc here.
hooked the Batt up, no smoke (good sign)
Turned the ignition on, no smoke (better sign)
bumped the starter, engine turned over (getting stoked!)
Full on cranked the engine....it fired and ran beutifully (AWESOME!)
Thought I was done (not the case)
oil guage is pegged to the right, speedo, tach, volt guage work great, fuel guage no workie, dont know about the temp, as I didnt run the truck but for a few moments (late here, wifies sleepin') elec. fan works (manual on/off not on T-stat)
Headlights, tail lights, running lights, guage lights dont work...
turn signals, when you put the flipper on the colum left the front signal and panel indicator come on solid, tail signal doesnt work and same exact issue with the right side.
Quite truthfully I havent put a guage to it yet, it was late enough and I was tired enough I felt it prudent to do to wrap up no brainer work, walk away and start troubleshooting when I'm fresh and wont get frustrated fast.
I did check all the fuses, none blown
I did ground everything but its kinda sounding like grounding issue to me, I just wanted to bench wrench it before I start doing the real thing tomorrow and looking for some insight as to what common stuff I havent thought of.
check power on both sides of the fuses, check power to the light switch, run a known ground via jumper cable to front of truck and check the grounds.....
anything else I know I'm forgetting?
good part is I havent beaten my head against the wall yet....I'm saving that for tomorrow...
BTW thanks for the help Doc, everything you told me having to do with the ignition and start system was spot on as evident by the cranking, starting and lack of smoke release....
oh one last thing a quick tip for ya shadetree folks, go to radio shack look through their tech parts drawer and get their sheilded multi plug connector assembly, prewire your starter whilst it is out of your vehicle, then when you install it all you gotta do is plug it in (once you wire the other side)....best $3.50 I've spent in a long time!
Last edited by Kallie49; 06-30-2006 at 12:07 AM.
Oil Gauge..peg to the right..No Sender wire connected..OR wrong resistance sender..
Check continuity from the "S" terminal on the gauge to the sender wire in the engine bay..DVOM set for OHMS, R X 1 , Calibrated 000..It should read 000 if the wire is good..
Fuel Gauge, No indication, Ground the sender wire at the tank it should peg one way or the other..Then, if it does, remove the wire and it should peg in the opposite direction..If you have that the gauge is working..If not ..check for power at the gauge, If you have a full 12 volts, then check your gauge ground and test with the sender wire open then grounded again..
If the gauge works, Replace the wire on the sender and run a known good ground to the sender body or float egress door..note reading on the gauge..If it is reporting, install a ground wire and properly bond it to the system ground buss.
Next run the engine and check the Temp gauge , and automatic switching for the fans..post back on that progress..
Headlights, Find the source of power for your headlight switch, be sure you have 12 volts there, If not follow it back to the fuse buss, or that might pick up power at the fuse link terminal..Some are wired that way with a thermal reset on the panel switch..find and fix that wire and it should heat up the lighting system..If you have power, but no lights, then check the system grounds. Check your Hi/Low Beam switch also..
Turn-signals, Do the brake lights work? and do they share a filament with the signal system? If the brake lamps are dead also, it may be as simple as the rear harness plug isn't plugged in..check that first..
The reason you get steady fronts is because there isn't enough load on the system to cause the flash, Go to the rear, pull either bulb and check to be sure it is the right bulb..(for the socket) , Then carefully with the signal selected for that side on, measure the pad inside the socket to ground, It should read 12 volts..If not back track it to the plug, then the steering column..If 12 volts are good, add a known good ground..that's what it is missing.
If they still won't work, check your column plug, Is it wired correctly for the rears and brake lamps (Shared system) If so , you have a problem within the signal switch assembly, or the harness between the top and bottom of the column..
That should only take an hour or so to shake down, and depending on what the corrections are needed, a few to finish..
Run a properly gauged Ground cable from the battery to any handy bolt at or near the starter, From that same bolt get a Battery cable at the parts store, that has two 3/8 ring terminals on each end and attach it there and to the Frame.
Next get some 10 gauge wire and ring terminals and run that from your bolt on the block to the Firewall, and another to the Alternator bracket or mount bolt.
Next get some Wire Braid, (Radio Shack) and install braid from the radiator support to the frame, Fenderwells to frame , hood to firewall, Doors to door posts, gas flap to body, tailgate / Trunk to body.
At each point the wire is grounded, Burnish ALL the paint and grease off to bare metal. Use a proper star-washer and lock. Use sheetmetal or Tech screws where no screws are available.
It sounds like a lot of work, but after you assemble all the parts, it's only a few hours to do..and you'll end up with a system that will work reliably for many years to come..and can eliminate that from your troubleshooting list.
Let us know..
Electronic & Electrical
Ok ladies and germs,
went trouble shootin today, made some good headway, here's what I figured out (resultant questions here in a min).
All grounds good, real good, ohmed the entire truck front to back systematically.
put old headlight switch in (worked just worn out) no fix, pulled it back out and hotwired the headlights and other lights, all that crap worked on hotwire.
ohmed the dimmer switch wires, good to go, checked new dimmer switch, good to go, checked brake light switch (only part I didnt replace) worked when it felt like it....replaced with new, got brake lights (WHOO HOO!)
took voltage reading on headlight inlet power....nada, ohmed entire headlight power wire all the way to the fuse block, no go....voltage on one side of the fuse and the output side failed ohm test....this got me to thinking that I had a bad connection in the block itself....
took fuse panel out and cut loom open, found headlight power wire and found something interesting.....that the headlight power wire did not go to the headlight power fuse slot.....it went to the radio slot...the manufacture dumb thumbed it in the wrong spot....switched it into the proper location and holy crapola the entire light system works!
one problem down.
ohmed oil pressure send unit....it failed, contact to VDO in work (NIB guages and senders)
turn signals, I replaced the rear tail lights with LED brights in back and LED brights in front...therefore my theory is that the switch relays dont have enough load to actually blink....they come on solid....
my question, do thay make a no load relay for LED's? if so whats the P/N....I need to get a pair...
Doc thanks in advance, I know you'll be the one to answer this most likly
had a change of plans and a free ticket to the honky expo popped up (Nascar Pepsi 400) so I wont be wrenchin tomorrow....oh well...so close
Sounds like you have it all under control now..as soon as new parts are here..Shows you the status of QC now a days..(Harness mis-wired, bad OBF senders..)
One Reason Why I always advocate checking replacement parts when you buy them at the auto parts store on things like: modules, Alternators, Starters, and anything else electrical they can test before you leave..Seen too many dead right over the counter..
And BOY..does that screw up your troubleshoot..(Can't be bad..It's brand new!")...
Anyway, on your turn signals..you are 100% correct..not enough load to flash them..You have a couple of options..You can replace the flash unit with a solid state unit that is designed to work with LED's...Or you can go load resistors..I have no numbers for these..but places like Auto zombie should stock them .. (If the sell LED's they should have them..)
There is a stop gap measure you can use, (Or make it permanent If you want..), Simply add a set of lamps and sockets on the signal wire and hide them in the trunk..(or where ever you can hide the lamps) The system will function normally, and should see you through until you get the flasher or load resistors..I've even heard of guy's hiding them under the seats..(don't advise it though..)
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