Question about 1993 Jeep Wrangler

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No spark When I test the electrical leads going into the coil, it reads 12.5 to 13 volts as long as its not connected to the coil. When I plug it into the coil, it reads 0 to 0.1. I tried a new coil with the same result.

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  • Jeep Master
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I don't think you are interpreting what you are reading correctly.

The ignition coil in a conventional system is supplied with 12 V when the key is turned on and the system modulates the ground side of the coil via a power transistor controlled by a bit of electronics that receives a signal from a pickup coil in the distributor.
If the coil is showing this low voltage, the power transistor in the ignition module has failed and is tying the low side of the coil primary to ground.

Just to make sure, check the current being drawn by the coil primary by putting your meter in series with the 12 V feed.
If your multimeter is equipped as most, it will have a 10 UNfused range.
Do not connect the last lead before tapping it while watching your meter display to ensure it doesn't exceed 10 Amps - it might, and the meter cannot protect itself on that range.

It sounds a lot like the ignition module has failed.

Posted on Aug 08, 2008

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2 Answers

Car runs great!! except when it rains.. it just sputters. missing splash guard somewhere?


Year make model and engion would help improve your odds of getting the right help

Oct 26, 2015 | Cars & Trucks

Tip

Engine electricals




3) Spark: From battery to spark plug

The battery is the source of stored electrical power in the vehicle. A voltmeter between the terminals of a healthy battery should read 12.5 volts. A reading of 12.2 volts indicates a flat battery and a reading of 10.4 volts indicates a dead cell (each cell beingabout 2 volts). A battery should be capable of sustaining high current, as needed by the starter motor when turning the engine over. When the car is running the voltage measured across the terminals shouldbe between 14.2 and 14.5 volts. The value is the voltage being supplied to the battery by the output charge from the alternator. THis charging voltage should not alter much when additional load is applied to the battery (head lights on etc).
When the ignition key is turned to the second position,often referred to as 'key on engine off', all car functions are powered up including lights and fuel pump. When the key is turned to position 3 many ancillary functions are temporarily interrupted to allow the battery to meet the extra needs of the starter motor. Electrical charge from the starter switch passes through a master fuse and starter relay before energizing the starter solenoid. The starter solenoid moves the pinion gear on the starter motor to engage with peripheral teeth of the flywheel. Simultaneously, heavy copper contacts are bridged by this same movement causing the starter motor coils to become energized thereby turning the engine over.
During the ignition process electrical charge passes through the primary windings of the ignition coil(s). The engine control unit (ECU), taking signalsfrom the engine crank position sensor, collapses the field of the coil(s) appropriate to the cylinder requiring ignition. As the field collapses the secondary coil windings discharge very high voltage through the high tension lead to the spark plug. The charge is so high that at the spark plug gap the charge jumps across with a spark. The compressed fuel air mixture in the cylinder is ignited by this spark.
Checking the spark process starts with the plugs. The condition of the removed plugs reveals a lot about the nature of the ignition within the cylinders. Dark sooty deposits indicate overly rich fuel air mix and glazed plugs indicate overly hot lean mixtures. Removing the plugs (with the fuel pump relay unplugged) and holding the screw threads to the cylinder head whilst turning the engine over will reveal the quality of spark. The spark holders and leads should be examined for discharge through the insulation to the cylinder head. Removing the leads from the coil should reveal sparks emanating from the exposed connectors. Failure to see sparks at this point indicatesa failed coil (especially if neighboring coils show good spark) or a failed crank sensor if all coils show no spark.
NEXT 1.1 MAF Mass Air Flow sensor

on Jul 15, 2011 | Mercedes-Benz E-Class Cars & Trucks

3 Answers

How do i test the ignition coil to know if its good or bad


With the vehicle in 'Park'[Auto] or 'Neutral' and hand brake on [Manual], open the bonnet and locate the ignition coil.
1. Ensure the lead is fully engaged [and that all wiring connections are tightened and free from dirt and corrosion] then follow it to the distributor cap and check that the other end is properly connected and the plug leads are also.
2. Remove a spark plug lead at the plug then remove the plug.
3. Connect the removed plug to it's lead and while holding the threaded portion of the plug in positive contact with bare metal on the engine [exhaust manifold] have someone turn the ignition key to crank the engine.
WARNING: Be careful if the engine is hot and wear gloves and use pliers with insulated handles when holding the test plug.
4. As the engine is turning over inspect the spark plug electrodes for any sign of sparking. A blue spark is what you want to see. Orange spark or none at all is bad news for the coil which needs to be replaced.
5. When you're done, replace everything properly, account for all tools and remember a clean engine is a serviceable engine. 25325059-xy42b42qawgpyeebopf3rzcc-3-0.jpg

Dec 16, 2014 | Cars & Trucks

2 Answers

Can I test an ignition module on an onan engine with a volt, ohm or amp meter?


well sure you can, allthough if you have allready replaced the coil and plug , i can't see why you'd need to , it's the last thing there is to replace , but if youd like to anyway , just ground the black lead of volt meter anywhere on engine thats not painted or rusty , hold red lead on - side of coil (its the one with half the battery voltage on it) and turn engine over slow as possible you should see the volts rise and fall as it turns over , if not the ign module is not working
also i question why does this have a condenser if it has electronic ign ? cant say id ever seen that before .

Sep 24, 2014 | Cars & Trucks

1 Answer

87 Toyota p/u 4x4 turns over won't start no spark at coil coil has 12 volts on both wires why is this should I have 12 volts on wires going to pickup in the distributor if so which wires should be hot???


12 volts at the low tension wire , hundreds at HT (high tension ) leads , they go to each plug, dont try testing them with a volt meter you will blow it up , and your hand as well,take one plug out , put the ht lead on it rest plug against the engine block , get someone to crank engine and watch plug to make sure you have a good spark, if not change the ign coil/s

Jul 06, 2014 | Cars & Trucks

1 Answer

How to check ignition coil for proper operation


  1. Connect an ohmmeter between the TACH and BAT terminals in the distributor cap. The primary coil resistance should be 0 or nearly 0 ohms . If not replace the coil.
  2. To check the coil secondary resistance, connect an ohmmeter between the rotor button and the BAT terminal. Note the reading. Connect the ohmmeter between the rotor button and the TACH terminal. Note the reading. The resistance in both cases should be between 6,000 and 30,000 ohms. Be sure to test between the rotor button and both the BAT and TACH terminals.
  3. Replace the coil only if the readings in Step 1 and Step 2 are infinite resistance or out of specification.
jturcotte_2418.gif





All tests included below.

The symptoms of a defective component within the HEI system are exactly the same as those you would encounter in a conventional system. Some of these symptoms are:


Hard or No Starting Rough Idle Poor Fuel Economy Engine misses under load or while accelerating.
If you suspect a problem in your ignition system, there are certain preliminary checks which you should carry out before you begin to check the electronic portions of the system. First, it is extremely important to make sure the vehicle battery is in a good state of charge. A defective or poorly charged battery will cause the various components of the ignition system to read incorrectly when they are being tested. Second, make sure all wiring connections are clean and tight, not only at the battery, but also at the distributor cap, ignition coil, and at the electronic control module.
Instruments designed specifically for testing HEI systems are available from several tool manufacturers. Some of these will even test the module itself. However, the tests given in this section will require only an ohmmeter and a voltmeter.

CAUTION The HEI ignition system can generate voltage of 30,000-50,000 volts. When testing the system, DO NOT hold a spark plug wire while the engine is running or cranking. Personal injury and or damage to the ignition system may result if this caution is not followed.
Since the only change between electronic and conventional ignition systems is in the distributor component area, it is imperative to check the secondary ignition circuit first. If the secondary circuit checks out properly, then the engine condition is probably not the fault of the ignition system.
If the engine won't start, perform this test. This will narrow the problem area down considerably.
  1. Remove one of the plug wires and insert a HEI spark tester tool in the plug socket.
  2. Ground the spark tester to the block and crank the engine. DO NOT touch the spark plug wire while the engine is cranking.
  3. The spark should be crisp and bright blue in color. If a normal spark occurs, try each spark plug wire until a no spark condition or a weak orange color spark is found. If all sparks are good, the problem is probably not in the ignition system. Check for fuel system problems, or fouled spark plugs.

If no spark occurs, check for the presence of normal battery voltage at the battery (BAT) terminal in the distributor cap. The ignition switch must be in the ON position for this test. Either a voltmeter or a test light may be used for this test. Connect the test light wire to ground and the probe end to the BAT terminal at the distributor. If the light comes on, you have voltage to the distributor. If the light fails to come on, this indicates an open circuit in the ignition primary wiring leading to the distributor. In this case, you will have to check wiring continuity back to the ignition switch using a test light. If there is battery voltage at the BAT terminal, but no spark at the plugs, then the problem lies within the distributor assembly. Go on to the distributor components test section.


If the engine runs, but runs roughly or cuts out, make sure the plug wires are in good shape first. There should be no obvious cracks or breaks. You can check the plug wires with an ohmmeter, but do not pierce the wires with a probe.
If the plug wires are OK, remove the cap assembly and check for moisture, cracks, chips, carbon tracks, or any other high voltage leaks or failures. Replace the cap if any defects are found. Make sure the timer wheel rotates when the engine is cranked. If everything is all right so far, go on to the distributor components test section.
DISTRIBUTOR COMPONENTS TESTINGSee Figures 2 and 3
If the trouble has been narrowed down to the units within the distributor, the following tests can help pinpoint the defective component. An ohmmeter with both high and low ranges should be used. These tests are made with the cap assembly removed and the battery wire disconnected. If a tachometer is connected to the TACH terminal, disconnect it before making these tests.
  1. Connect an ohmmeter between the TACH and BAT terminals in the distributor cap. The primary coil resistance should be 0&omega or nearly 0&omega . If not replace the coil.
  2. To check the coil secondary resistance, connect an ohmmeter between the rotor button and the BAT terminal. Note the reading. Connect the ohmmeter between the rotor button and the TACH terminal. Note the reading. The resistance in both cases should be between 6,000 and 30,000&omega. Be sure to test between the rotor button and both the BAT and TACH terminals.
  3. Replace the coil only if the readings in Step 1 and Step 2 are infinite resistance or out of specification.

jturcotte_2419.gif

Fig. Fig. 2: Checking coil resistance. Ohmmeter 1 shows primary test. Ohmmeter 2 shows secondary test.
These resistance checks will not disclose shorted coil windings. This condition can only be detected with scope analysis or a suitably designed coil tester. If these instruments are unavailable, replace the coil with a known good coil as a final coil test.

  1. To test the pick-up coil, first disconnect the white and green module leads. Set the ohmmeter on the high scale and connect it between a ground and either the white or green lead. Any resistance measurement less than infinite requires replacement of the pick-up coil.
  2. Pick-up coil continuity is tested by connecting the ohmmeter (on low range) between the white and green leads. Normal resistance is between 650 and 850&omega, or 500 and 1,500&omega on 1977 and later models. Move the vacuum advance arm while performing this test (early models). This will detect any break in coil continuity. Such a condition can cause intermittent misfiring. Replace the pick-up coil if the reading is outside the specified limits.
  3. If no defects have been found at this time, and you still have a problem, then the module will have to be checked. If you do not have access to a module tester, the only possible alternative is a substitution test. If the module fails the substitution test, replace it.

jturcotte_2420.gif

Fig. Fig. 3: Pick-up coil testing

Oct 24, 2011 | 1989 Buick Park Avenue

1 Answer

95 astro has no spark to the coil what next


Try this tips:
1. Check the battery voltage at the battery with the digital volt/ohm meter. Set the meter to "Volts D/C" and touch the black meter lead to the negative battery post and the red meter lead to the positive post. A fully charged battery will measure 12.7 volts or more. A measurement of 12.5 volts is considered discharged, and the battery should be charged before any further testing. Any measurement below 11 volts indicates a severely discharged battery--the battery is most likely damaged and should be replaced. If the battery measures above 12.7 volts, proceed to the next step.

2. Check the starter for battery voltage by touching the red (positive) meter lead to the battery cable terminal on the back of the starter and the black (negative) lead to the chassis. The voltage reading should be approximately the same as the measurement at the battery. If the reading is lower than battery voltage, check for bad connections at the cables on the battery and the starter or ground cable.

Check for ignition switch signal at the purple wire on the back of the starter. When the key is turned to the "Start" position this wire should measure battery voltage. If the reading is less than battery voltage, or zero volts, check the fusible links (orange wires) on the back of the starter. If the fusible links are intact and not burned or broken, replace the ignition switch. If battery voltage is present at the purple wire, and the starter doesn't turn, replace the starter. If the voltage measurements at the starter are correct, and the starter cranks the engine over when the key is turned to the start position, proceed to the next step.

3. Remove the air duct attached to the throttle body, and spray a liberal amount of the carburetor spray into the throttle body. Replace the hose, and try to start the engine. If the engine starts, the fuel pump is not supplying fuel or the ignition module is not pulsing the injectors. Check the fuel pump fuse located in the under-hood fuse block. If it is good, check for power at the fuel pump electrical connector located near the rear of the fuel tank on the driver's side of the van. In the Chevy Astro van, power is supplied to the fuel pump by the the gray wire on the electrical connector when the engine is being cranked. If power is supplied, hitting the fuel tank with the flat side of a hammer while someone else is turning the ignition key to start will sometimes bump the fuel pump enough to allow it to start. If the fuel pump checks good, proceed to the next step.

4. Check for spark. Disconnect the coil wire at the ignition coil, and try to start the engine. If no spark occurs, replace the coil and ignition module. If a strong spark occurs, plug the wire back in, and remove a spark plug wire from a spark plug and repeat the test. If a spark is not present, replace the spark plug wires, and distributor cap and rotor.


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Jan 12, 2011 | 1995 Chevrolet Astro

1 Answer

I am trying to replace the igniyion coil but i dont know which one is bad


  • Unplug the spark plug wires from the coil and label the wires if necessary for proper installation.
  • 4 Unplug the pack's electrical connector and remove the coil pack from the engine, using a wrench or ratchet and socket if necessary. If your coil pack is mounted on the back of the engine, raise the front of the vehicle and safely support it on two jack stands to reach the coil pack from underneath the engine.
  • 5 Set your ohmmeter to the 20000 ohms range. Turn on your meter and touch the spark plug wire terminals on one of the coils with the meter leads. You may get a reading between 5000 to 15000 ohms, depending on your particular model. This checks the secondary resistance.
  • 6 Set your ohmmeter to the 10 ohms range, and touch the terminal B+ (usually the center prong on the coil pack electrical connector) with one of the meter test leads, and touch the corresponding coil prong on the electrical connector with the other test lead. You may get a reading between 0.3 and 1.0 or more, depending on your particular model. This checks the primary resistance on each coil.
  • 7 Repeat steps 6 and 7 for each coil in the pack assembly, and compare your resistance readings to the specifications given on your vehicle service manual (see "Tips"). If your readings are out of range, replace the coil or coils as necessary.


  • Read more: How to Check Coil Packs With a Voltage Meter ' eHow.com http://www.ehow.com/how_4912368_check-coil-packs-voltage-meter.html#ixzz13fJECvLx

    Oct 28, 2010 | 1997 Toyota Tercel

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