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Discussion Starter #1
My 1st car and I'm in need of a detailed explanation as to how to use a multimeter to trace the ignition as I've no spark at the coil. Coil and amp are new, just need how to trace signal. Perhaps someone knows of a "Dummies" instruction. I've got the Rave and found testing procedures in the Injector Section but it's Greek to me. Also, my Rave features 87,88, 89, & 90 years but the 1990 section doesn't have a test instruction details as robust as the info for the earlier years. In summary by "Dummies" I mean: 1. What setting do I set the meter for? 2. Where to place the + and - at the coil? 3. Etc.? Thanks for reading. o_O
 

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Discussion Starter #2
Perhaps I've no spark due to a bad Alt? Or perhaps I'm looking in the wrong place. A youtube video I watched suggested testing the Alt and I followed their instruction minus removing the Alt from the car. Set the meter to "Diode" and instead of have no values I got values from switching the + and - leads. According to this video, I should have no value with the black lead on the Alt post. I get lots of different readout values when testing - the display jumps around numerous different values very quickly. I didn't remove the Alts wired connections, I just tested with the Alt in the truck. So, should I assume I've a bad diode that inhibits spark causing her to not start?
 

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"Ahem Ahem, Oh lost soul, let me bestow upon you my great wisdom!" Blah blah blah ok sorry on to the actual helpfulness

So no spark at the coil, are you certain? A good way to test is with an inline spark tester, super cheap from amazon, it plugs inline between the distributor and any of the wires and flashes (as your cranking) if there's a spark, no flashy, no sparky. If there is spark, the color of the spark matters too, you want a bright white spark. If you have a dull yellow/orange spark, it may not be enough spark to actually ignite the fuel and start the engine. So if there is spark, white spark good, orange spark bad :).


If you have no spark, that could be a few things. It could be the the distributor cap or rotor are worn out, and should be replaced. this is likely the case if you have spark from the coil to the distributor, but nothing on any of the wires going to the plugs (check with the spark tester above). If there's no spark anywhere, it could be the ignition amplifier module, which is a little box on the side of the distributor. They are not the most reliable things and have a tendency to die without warning. They are pretty cheap and easy to find, and not too hard to replace. There is also a relocation kit that moves it away from the distributor so it doesn't get hot.



In terms of the coil itself, measuring voltage across it is a bit tricky. If you disconnect the wire from the + side of the coil, with the ignition on you should see 12V on that wire (red wire from multimeter (set to DC volts) on wire, black wire on a ground, some exposed metal bit in the engine bay like a bolt). The wire on the negative side is not a ground, it goes to the ignition amplifier on the distributor, so you wont be able to get a reading on that. If you have 12V on the + wire, you can check the resistance across the coil to see if the coil itself is bad. Unplug the lead from the center of the coil, set the multimeter to resistance (ohms) and measure (with the ignition OFF OFF OFF) from the plus terminal to the center of the coil (inside where the spark lug lead connects). You should see several thousand ohms, likely more than 5,000 but less than 20,000. Then check the resistance across the + and - terminals, it should be a lot less, on the order of a couple ohms or less than one ohm. If the readings are wayy ff from these, the coil itself may be bad (not a super common failure, but an easy cheap fix).
289070


I hope some of this was useful, if you have any further questions don't hesitate to ask, and let us know what you find out.
 

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Discussion Starter #4
Lots of info, thanks. Cap/rotor are new as stated but they aren't getting any spark from coil. Coil/amp are also new (already relocated). So, tracing the lines are more critical than testing the components ie amp/coil/cap/rotor etc. I just don't know how to test the lines to and from the coil. Is this a poor plan?
 

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Lots of info, thanks. Cap/rotor are new as stated but they aren't getting any spark from coil. Coil/amp are also new (already relocated). So, tracing the lines are more critical than testing the components ie amp/coil/cap/rotor etc. I just don't know how to test the lines to and from the coil. Is this a poor plan?
Doing forget just because it’s new doesn’t mean to say it’s not faulty!!
been there done that.
test everything to make sure;)
 

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If you have 12v at the coil as described above by LancL.. red multimeter lead to + on coil ignition on black multimeter lead to a good earth point, meter on 12v DC,
try pulling the HT lead from the centre of distributor cap and put the end near an earth point and crank the engine is there a spark from that lead? if so your problem is from there on, if not you need to check things like is the 12v supply to the coil disappearing/ collapsing when you crank the engine etc
 

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Some good advice to check through in above posts.

I'd firstly check that you've got supply at the coil plus terminal as initially if that's not coming live whenever ignition is turned on then nothing at all will work in the entire ignition system. It's the gateway to establish first. No supply here and you are probably looking at ignition switch or route from it to the coil.

If you've got the voltage in place above, then remove the negative coil lead. Now using a wire direct to earth, touching the negative terminal should fire a spark each time you touch. That would verify that you've got HT output too if it sparks.

Then that leaves the pulse generated from distributor through the amp to switch the negative lead up/down (coils are all switched with constant + supply and - going on/off) so if you can induce the coil to fire manually as above, then the pulse switching is suspect.
We've had on here wrong connections to from amp before that did this (no switching) with new components, so double check coneections, instructions and colours of this section. Believe there were some kits with suspect instructions/swapped colours, if memory serves me right.
 

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Lots of info, thanks. Cap/rotor are new as stated but they aren't getting any spark from coil. Coil/amp are also new (already relocated). So, tracing the lines are more critical than testing the components ie amp/coil/cap/rotor etc. I just don't know how to test the lines to and from the coil. Is this a poor plan?
Your original post does mention the new coil and amp, sorry I missed that, but you didn't say new cap/rotor. Regardless, cortinamk2 is correct, we have seen many a faulty on straight out of the box, new doesn't always mean functional!

I described how to test the wiring from the coil, see original post to check the 12V source (+ side), and use RRLondon's method above to manually induce a spark touching the negative side wire to ground. If you don't have 12V with the ignition on, there's an issue with the source wiring. If you do, but touching the negative to ground doesn't get you a spark, then the coils is bad. If it does, then the problem is the ignition amp, or it's wiring. It is rather unlikely there is damaged wiring somewhere in the loom, so it's really worth making sure the components are actually working first before hunting for continuity breaks in the wiring harness.
 

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Discussion Starter #9
a LITTLE progress. Multimeter battery test returns 12.3v but only 11.3 at the coil when ignition is on and the positive lead on coil + with the - lead on the plenum. Is this the possible problem? Testing coil seems to be ok with returning ohm values of 1.9 on the posts and 8.55 from the coils center. So, I'm not sure how the low 11.3 value at coil can be fixed if it is in fact my problem? Thank you.
 

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Battery at 12.3volt is getting toward marginal if it's fully charged. Should be around 12.6 to 12.9volt for a healthy battery.

Charge battery for a couple of hours, leave for 20mins to settle volts and report what it sits at.

Those volts should still make a spark manually though.

To supply max volts to coil, you can just rig straight from battery + to the coil + and then try to fire it. It will take out any loom error. This is classic "hotwire" method that people, ahem, without keys use to start a car they don't own. DON'T touch the end of that wire on any other metal though, best to connect onto coil first and get someone to hold it onto battery to then let you try to start.

Let us know how you get on.
 

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Discussion Starter #11
The pos+ side of the coil gets the resister/capacitor correct? (or whatever the item may be called)
 

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The coil condenser (small cylinder with a single wire) goes on the negative side of the coil.
 

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Here's my odd experience, not implying this is the issue with what you're dealing with. On my '85, the ignition box finally failed (factory installed electronic ignition, similar to the late '70's Ford style), decided to switch over to the newer type ignition since these bits are easier to obtain here in the States. New distributor, coil and amplifier relocation kit. Had to relocate it anyway, amplifier would not clear the PS pump, wouldn't allow distributor to fully seat. Also had to adapt original gear to new distributor.

I had spark, then none, back to spark, then none again.....if I ran the coil lead anywhere near the amplifier wires, it'd kill the spark. Isolated the coil lead completely from all other wires, have had spark since.

Still wasn't right, spark was gradually getting weak until I installed a Red rotor from AB. All has been good now for about 4,000 miles.
 

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Discussion Starter #14
The pos+ side of the coil gets the resister/capacitor correct? (or whatever the item may be called)
OK, I'm back after my spark after a hellacious work week. I reconnected the condenser correctly yet still no spark. Volts at battery are now 12.5 and volts at coil with its ignition on is 11.5. Will running the hack wire from the battery be my next best step? Again, she's no spark but has good new coil and amp.
 

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If no spark then, you have next got to rig a temporary earth lead that you can just touch onto the coil - negative post.

With confirmed power at the + coil post, when you just touch the temporary - lead it should fire a spark each time you touch the negative post onto the coil.
If that works, then you are looking at the amp as all that is doing is flashing that earth post ( in time with the engine's speed) .
To make that clear, the amp output is switching a negative connection up and down to make sparks from a coil that has constant positive + supply.
 

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Discussion Starter #17
Ok, I'll try the test but before I do I'd like to get this out of the way 1st: When wiring my coil I may have botched its connections as I did discover I did have the Condenser on the wrong side - It's now bolted to the negative side. Ok, both wire from MAF and black wire from Ignition Amp combine and get the positive side of the coil with the Condenser. And the white Amp wire combines with the white wire that exits the loom that is found on the body side which also heads to the firewall. Correct? Once correct I'll run her jumper wires from the battery.
 

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Ok, just verified on mine.

White (from amp) to + coil post.
White with black tracer ( from amp) to - coil post.
Lead from MAF loom and further back to the bulkhead, also to - coil post ( this one is the trigger count wire to the ecu for pulse count to run the injection system) it won't stop it sparking but will stop it running as ecu logic will see no revs reported. It's just an observer.

The condenser, mine hasn't got one. I don't understand why it's fitted though as usually they are used for old type points ignition distributor to prevent the contacts burning.
For a trial I'd remove the connection of this to assess as if it gives a constant earth for any reason then it won't spark at all.
 

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Discussion Starter #20
Ok, just verified on mine.

White (from amp) to + coil post.
White with black tracer ( from amp) to - coil post.
Lead from MAF loom and further back to the bulkhead, also to - coil post ( this one is the trigger count wire to the ecu for pulse count to run the injection system) it won't stop it sparking but will stop it running as ecu logic will see no revs reported. It's just an observer.

The condenser, mine hasn't got one. I don't understand why it's fitted though as usually they are used for old type points ignition distributor to prevent the contacts burning.
For a trial I'd remove the connection of this to assess as if it gives a constant earth for any reason then it won't spark at all.
Thanks for the wiring info. Tried it with and without the Condenser without success. Will try the "hack" wire jumps from the battery next......
 
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