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GMC - its broke - HELP


Jack

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Back to the drawing board..............

 

 

 

  1. Just put the loom connection back on and 10v was recorded
  2. took that off and put the indicator connection on and the volts measured 3.5.............

 

:???:???:???:???:???

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Thought you had a 12v system? :-D The battery should be giving out 12 volts if fully charged. Sure it doesn't just need charging?

 

Sounds very much like a duff battery - it might register a good (not that yours does...) voltage with no load, but as soon as you put any load on it, a cell breaks down.

 

Try puting the battery on something else and see what that vehicle does. Or try running anything 12v off it with jump leads.

 

How about sticking another battery on the jimmy and see what happens?

 

What resistance reading do you get across the battery leads without the battery on?

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unanimous blown battery, and probably a bit of corrosion on contacts. Next bit a known good battery. When started check the voltage at the battery. With warning kight out you should get about 13.6 13.8 any more or less problems. If less check drive belt for alternator first, if more alternator shunts us. You can jump start if yiu wish, then check voltage. If the voltage is in the range, but on leaving or won't re start confirms battery. First rule with electrickicery do things in a logical order.

First from description battery

Second if a relitivley new battery, voltage at charge, if that's OK battery back under garuntee.

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Thanks chaps!

 

 

 

  1. I put Mrs Becketts battery on there from her car and still everything is dead
  2. I had the battery on charge for a day but was still reading around 10v

 

:???:???

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Thanks chaps!

 

 

 

  1. I put Mrs Becketts battery on there from her car and still everything is dead

  2. I had the battery on charge for a day but was still reading around 10v

:???:???

 

Could be a shagged meter:coffee:

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Battery is dead, thats for sure. Most likley cause if the system is overcharging. Check earth, use a jump lead on battery to an earth on a known clean place on the vehicle. There does sound to be a multiple problem. Does your starter work independent of the ignition switch? If it doesn't life will be a bit easier as the first place everything meets is the ignition switch.

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Battery is dead, thats for sure. Most likley cause if the system is overcharging. Check earth, use a jump lead on battery to an earth on a known clean place on the vehicle. There does sound to be a multiple problem. Does your starter work independent of the ignition switch? If it doesn't life will be a bit easier as the first place everything meets is the ignition switch.

 

 

That I don't know Tony but if there is power to the starting motor then it should turn - shouldn't it???

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A fully charged battery should be reading around 12.5v to 13.8v. depending on age/condition. 10v fully charged says there is an issue with the battery.

 

An old trick I was taught to check a starter out was to take a large wooden handeld screwdriver and short the solenoid switch terminals out (disconnect coil HT lead first) - if the engine spins over the starter is fine, if not there's an issue either with the solenoid or the starter windings.

 

No idea if that's any help to you mate!!

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Jack do this:

1-- Fit good known battery, well charged, reading over 12volts ish

2-- Remove clean and Vaseline all connections for all the -ve wires ie all chassis connections, then do up tight on clean surfaces.

3-- Remove +ve wire on battery and clean, Vaseline, re tighten, the other end should go directly to the starter, remove this connection and clean, Vaseline, re tighten. NOTE do NOT connect any other wires to the Starter connection.

MOST IMPORTANT

Remove fan belt so alternator can not turn, otherwise with its wiring disconnected it could get damaged.

4-- At this stage the only thing connected is the Starter motor, so by pushing the starter peddle on the floor the starter should crank the engine over, it will not start as there should not be any connections to the coil so no spark, so no start....

 

Try this if successful then move on to another bit, if engine turns over then fit your old battery and try again if it will not turn over you have a duff battery.

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Ok this is where we are at:

 

 

  1. Just put the volt meter on the battery with the leads on and it is registering 1.1v
  2. take the live lead off and the battery is giving out 8.9v
  3. put the lead back on and place meter on the live lead into the starting motor - it registers 1.1v
  4. undo the nut and take the live off the starting motor and it registers 8.9v again..........

 

So do I have a leak somewhere :???:???:???:???

 

If I understand this correctly, it sound like there is a short in the loom somewhere ( unless there is something still switched on ) as when you take the wiring off the volts jump up and when it is connected again the volts drop, what you need to do is get a D.C. clip-on ammeter to see what current is being drawn off the battery to cause the volts to drop that much !!

Also use a good charged battery as if there is an issue with a loom short on a good battery you can see by sparks when you connect the battery...

Be careful could cause a fire.

 

Ultimately get a vehicle wiring electrician to sort it out..

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Mike and Rcubed have asked most of the questions I'd thought of. So to recap. you operate starter and it just cliks. The battery is knackered. It started fine then suddenly wouldn't.

 

Leave aside the battery for the monent. The most likley is that something is dirty or brocken, neither could be obvious. Try taking a jump lead straight from the battery to the solinoid. Not knowning exacataly what it looks like is awkward. The power goes striaght from battery to one side of solonoid. This is a thick heavy wire. From the other side of the solonoid a thick wire will go into the starter motor. On the solonoid will be another connection or a bar switch if it is on a foot push. This connects the two thick cables and the starter is energised. Dirt on any of thses conatcts can cause the problem, same if any are loose. If you consider that on starting the motor is taking about 3, 600 watts, (12 volts X 180 amps = 3,600 watts) if artihmatic is right, more than a 3 bar electric fire, you understand there is a lot of power, if anything isn't perfect it will heat and burn or spark. The other thing is obviously pull the starter motor, check it and kick it over off the vehicle. A dam good thumping with a rubber hammer may work. Weve all got bogged on electrics, may be missing the obvious (Again!)

Edited by Tony B
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Try taking a jump lead straight from the battery to the solinoid. Not knowning exacataly what it looks like is awkward. The power goes striaght from battery to one side of solonoid.

 

A dam good thumping with a rubber hammer may work.

 

Tony,

 

You keep on about solenoids, but I am sure GMC's do not have them, it is like a Jeep, and many other vehicles of the era, just a main starter switch direct from battery. No wonder Jack is getting confused.

 

As for the rubber hammer, you might feel better after using it, but very doubtful of it curing anything :???

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Guest catweazle (Banned Member)
I would definitely feel better after using it, but not on the GMCstarter.:argh:

DO you have someone in mind?:rofl:

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Guest catweazle (Banned Member)
,

As for the rubber hammer, you might feel better after using it, but very doubtful of it curing anything :???

I know something it would cure.:-D

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I would definitely feel better after using it, but not on the GMCstarter.:argh:

Hmmm a rubber mallet yes I had one once, got wild with it too, don't ever throw one in a garage, I did, I threw it hard at the floor, it hit the floor then bounced up into the air like a rubber mallet would untill it hit the roof, but in between these two points was an 8 foot twin striplight.......................

 

Well................:argh::argh:

 

You would not believe how much tiding up the glass needed I was finding bits months afterwards...

 

Now I throw things outside.....:confused:

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Great stress reliver,the rubber hammer. Easier to carry than a rubber room. I was just wondering if the mechanicals of the starter could have stuck. Had a vehicle that worked for years, then did the same thing, when the starter was taken off the plate over the starting lug flew off, it had never been screwed on! :confused:

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