This page was last updated on $Date: 2000/03/06 00:01:11 $
I'm truly open for any additional input on this. Please feel free to add any ideas you may have (rather waiting for someone else to mention something obvious that I might have missed). Remember, I'm no expert, I'm just another shade-tree mechanic like most of the rest of you.
If you have any additions, send them to me embedded in the relevant area of the guide which you think that they should appear. Put your changes in ALL CAPS so that I can easily recognize them. To save everyone's time, don't post them back to the entire british-cars list, send them to me.
(For the new folks, I'm one of the british-car.old-pharts who was once a regular, but doesn't seem to post much anymore. But, I've learned immense amounts and gotten tons of support from the british-cars list and it's spinoffs ever since I first joined with a Triumph TR8 way back in 1989. Since then I've moved onto the Jag list, but I still read brit-cars to see what everyone's up to. Every once in awhile I arise from my dogmatic slumber and post some long-winded compilation like the following to try to make the world a better place for british-cars.)
I'll integrate any changes and repost the final form to the british-car archive so that it's available for the next time this question comes up.
/\ Lawrence Buja Climate and Global Dynamics Division \_][ firstname.lastname@example.org National Center for Atmospheric Research \_________________________Boulder,_Colorado___80307-3000__________
This guide assumes that your engine is not seized and that your ignition switch functions correctly.
One of the most basic tools is a copy of a wiring diagram for your car. Without this map, you can only guess at what the various wires and relays are doing.
Since it's really hard to see electricity, one should have a multi-meter (or at least a little test light) to act as your eyes. For our purposes here, a $20 Radio Shack multi-meter works as well as a $200 digital multimeter (DMM). Until I got a DMM, I was electro-phobic and wouldn't touch electrical problems. Now that I have one, I've tracked down and fixed numerous electrical bugs in my Jaguars. I consider a good DMM (Fluke 77) one of my more useful tools and wouldn't be without one. If just once you successfully fix your starting problem without having to pay a mechanic or having to buy an new battery or starter, you've more than recovered your investment. Test lights are not to be ignored. They have their own advantages which are discussed below.
A set of heavy-duty jumper cables comes in handy for delivering electricity to selected components and for testing your engine ground.
But, the most important tool is common sense. Bad things can happen if your starter decides to work when your car is in gear or you generate a spark near the battery when there's too much hydrogen loitering around from a recent charging session. So, be careful and try to exercise some basic precautions like:
Now, back to the usual suspects: 0) user-error, 1) battery, 2) bad connections, 3) bad relay, 4) bad starter.
Dead shorts can also drain a battery very quickly. Dead shorts typically result from insulation chaffing off wires and grounding against the chassis or electrical components failing.
The basic drill when a ground is suspected is:
Trying to debug automobile electrical problems with a multimeter is like trying to read fine print with an electron microscope; inconsequential details completely obscure what you're trying to figure out. As primitive as it is, the correct tool for automobile electrical problems is the test light. In trying to figure out a current drain on the battery the thing to do is to disconnect the negative battery lead and attach the ground clip of the test light to the negative battery post. Then touch the 'probe' to the negative battery clamp. (Got that? The test light is now in series with the entire electrical system) If you've got a significant drain the light will light up brightly, if not it won't. If it does light, debugging just means pulling out fuses until it turns off, then tracking down that particular path. Of course if it doesn't light, it means that your problem is something other than a static drain. The advantage of this approach is that it allows significant current to flow which can allow a relay to click on and turn on the real power hog, accounts better for nonlinear resistance components (such as light bulbs!), etc.
A handy tool for measuring current is your headlights. Do your headlights come on strongly? Their brightness is an indication of the general health of your battery. If they are bright and stay bright, your battery is probably good. If they dim greatly when you try to start the car, then your battery may near the end of it's lifespan.
Another thing to check is the age of the battery. If it's more than 5 years old, there's a good chance that it's tired and wishes to retire, if it hasn't done so already. A 4-5 year old battery, if not elderly, is considered rather mature.
Try cranking the motor with your DMM measuring the volts across the + and - battery terminals. The battery voltage should not go below 9-10 volts if the battery is good and fully charged. If the voltage drops below 7 volts and the battery is charged, the battery may be bad or you may have a ground somewhere in the electrical path or the starter bushings may be worn and the starter may be binding.
Try jump starting the car from another car or swap in a known good battery and see if the problem persists (it's considered good form to obtain permission from the replacement battery's owner before doing this). If it starts now, then either both your original battery and whatever method you used to check it are suspect or your battery connections were bad.
Bad ground connections are quite common in vintage cars which live in 4-season or wet climates. Temperature fluctuations can make marginal connections even worse. The first thing to do is clean up the battery terminals and the clamps on the wires going to the cables.
A cheap diagnostic for bad ground connections is to run a jumper cable directly from the appropriate battery ground terminal (-/black for neg grounded cars, +/red for pos ground) to your engine block. Connect the battery side first, then touch the other end of the jumper to the engine block. If you don't get a big nasty spark, you've done it right. If the car starts now, then one of your battery to engine-block ground connections is bad. This trick has worked for me personally in the past when an engine-chassis ground strap, which is underneath the car, lost contact.
Check the integrity of the hot side connections. This is somewhat trickier and requires both care and courage. Disconnecting the hot side connection (+/red for neg grounded cars, -/black for pos ground) from the battery helps to keep this task from getting too exciting. One-by-one, remove a wire from the back of the starter, gently clean the end with fine sandpaper, clean the lead on the starter and then reattach the wire. You can use your DMM to check the resistances of the various wires to ensure that the end connections of the wire aren't bad. Do them all. The courage part comes in if you are brave enough to try to jumper the starter directly. Usually this isn't necessary since cleaning the hot side connections should have taken care of any problems along this path. In any case, I won't describe the procedure. You're intelligent enough to either figure out a safe way to do it or to be content in the knowledge that you were smart enough to avoid trying to do something really stoopid. If it starts now, you got off cheap, 'cause from here on out you're going to be spending money.
[ I DON'T DISCUSS DETECTING BAD CRIMP CONNECTIONS. RESISTANCE TEST???]
For more modern, automatic transmission, cars, the fault may lie in a bad Park sensor. As a long-shot, you can try engaging the starter while wiggling the gear lever around in the Park position to see if anything happens.
[ CAN ANYONE PROVIDE ADDITIONAL DEBUGGING HINTS HERE??? ]
[ DOES ANYONE HAVE ANY OTHER RELAY DEBUGGING HINTS? ]
[ ANY HINTS FOR DETECTING A BAD IGNITION SWITCH?
Now we are reduced to suspecting either a bad starter or a bad starter solenoid. If you've got too much money, simply have someone install a new starter and solenoid and you are done with it. If you are cheap like me, pull the starter, field test it, attempt to fix it and if all else fails, take it to a local starter shop to be rebuilt.
The solenoid on the starter has TWO windings. Both windings are energized from the starting contacts on the ignition switch when you turn the key to the starting position.
Winding #1 is connected in series with the starter motor itself. That is, the current that comes from your ignition switch has to travel through the winding in the solenoid, through one pair of the brushes, through the commutator, through the armature, through the other pair of brushes, through the field windings and, through the ground of the of the starter, through the ground of the engine, through the ground strap between the engine and the chassis (or through the choke cable, if you forgot to put the ground strap back in the last time you pulled out the engine!) then through the chassis and, finally, through the negative battery cable back to the battery.
If the brushes do not make proper contact with the armature, chances are that you will hear a _click_ (or nothing at all) instead of a _CLICK_ when you turn the key.
Winding #1 is the one which does most of the work of engaging the pinion with the gear on the flywheel when you turn the switch. This winding is shorted out by the solenoid contacts when the starter is engaged. The contacts then supply the full amount juice from the big fat cable connected to the battery (and back to the battery as described above).
Winding #2 now is left to itself to keep the starter engaged until you release the ignition key.
> On this starter, all wires connect to one post of the solenoid;The big fat wire from the battery supplies the juice from the battery to the starter when you turn the key. Of the other wires connected to the same post, one comes from the generator/alternator (through the ammeter, if you've got one), the other runs to the ignition switch through the fuse box. Basically this terminal is the hottest point, electrically speaking, of the entire car. The white-brown wire is the one that supplies juice to the solenoid winding(s), as described earlier.
> the one that matters most is the battery cable. A couple of brown
> wires bolt to that post too, and a white-brown wire connects to a
> spade lug and runs to the ignition switch. That all works; all
> the ignition-related stuff (lights, fuel pump, etc) work when I
> turn the key.
Here's how I would go about troubleshooting your problem:
The solenoid should pull in with a good, solid CLICK and stay in that position until you disconnect the cable.
The starter should run freely, without the drive pinion being in the extended position. Don't do this for more than a few seconds!
The solenoid should now pull in, extend the drive pinion, close the contacts and the motor should be spinning. Again, don't do this for more than a few seconds at a time!
Here are a couple of things to keep in mind, if you decide to take the starter apart:
> I suppose the next step would be to check resistance across theAlthough I have probably half a dozen DMM's, I find it easier to use an analog voltmeter when working on cars (and boats). My favorite was a Simpson, model 260-7, which I unfortunately loaned to a fellow SOL'er a few years ago, and never got back.
> two poles of the solenoid and compare that against resistance from
> the input pole of the solenoid to ground on the block. I guess I
> should have asked Santa for a DMM... :-)
A simple gadget which I find very helpful when troubleshooting 12 volt circuits is an old taillight with a 25 watt lamp in it. I have connected two black wires with alligator clips on one side of the lamp. One wire is about six inches long and is useful for hanging the thing from anything that is grounded, that's nearby. The other black wire is about 20 feet long and is used for testing grounding problems, e.g. to test that dim taillight, I connect the short wire directly to the negative side of the battery and connect the long wire to the socket of the dim taillight. If the taillight gets brighter, I know that there is a bad ground somewhere between the battery and the taillight. On the other side of my test lamp I have a 20 foot red wire with a pointed test probe on the end. If I connect this probe to the hot terminal of the same dim taillight as before and the dim light gets dimmer, I know that there is a problem between the hot side of the battery and the taillight circuit (The additional current drawn by the test lamp = additional voltage drop). The test lamp is also handy for testing corroded fuse holders, flaky starter switch contacts etc., where a Digital Multimeter may happily show 12 volts even though there may be hundreds of ohms of resistance the circuit.
(One modification I would include next time I make one of these gadgets, would be to include a couple of 10 amp in-line fuses in each of the long cables.)
A voltmeter in a car (even in a ZX, whatever make of LJC that may be) is not a very good instrument for troubleshooting. A simple test lamp like the one I just described would work much better. If you hook it up directly across the battery you'll be able to tell, fairly accurately, what condition the battery is in, both under load and no-load. If the light goes from bright to close to nothing when you crank the starter, well let's hope that Sears is having a sale on DieHards this week. If the brightness of the lamp changes only slightly, then the battery is most likely not the problem.
It is possible for the starter push the ring-gear on the flywheel back to the point where the starter will no longer engage the ring gear. The symptoms are a starter that engages and whirrrs at high speed, but doesn't crank the engine. It has been confirmed that many TR-6 were shipped with ring-gears installed backwards after the factory switched from rear-engaging starters to front-engaging starters, but didn't bother to reverse their stock of already assembled flywheels. This left the beveled side of the ring-gear pointing away from the starter gear rather than toward the starter gear as it should for easier engagement.
I once saw an instance where either the starter relay failed or a wire got shorted in the starter circuit. The starter engaged and ran continuously, even though the engine was running and the key was turned off. The noise was horrendous. In this case, I quickly disconnected one of the cables from the battery and let the unfortunate woman call AAA.
[ ANYTHING ELSE??? ]
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