I have power to the HEI distributor, but nothing down the plug wires. I would like a test to see if the internal(removable) coil is good, maybe a resistance value

The GM HEI distributor is one of the easiest ignition systems ever created. The only thing below the module would be the shaft and drive gear. If the rotor turns when you crank the engine, it is most likely good. If it doesn't, You will need to pull the distributor from the engine to check the gear at the bottom of the distributor and the gear on the cam. The other thing to remember is that the distributor grounds through the engine block. Make sure that there is a good engine ground.

this generation of gm vehicles is easy to troubleshoot. the engine needs 3 things to run: compression, fuel, and spark. since you mention fire, i assume you have no spark.

disconnect any random spark plug wire and connect the end to a hei spark tester. crank engine and observe for spark. if you have no spark, disconnect the center terminal of the distributor cap and use the hei tester in the same manner. spark means cap and rotor bad or bad plug wireset. no spark means make more checks.

check for battery voltage and good ground on distributor. check for open or shorted ignition module or ignition coil windings. if power and ground is present and ignition coil tests ok, check for ignition pulses at coil primary. if you have no ignition pulses feeding the coil, change the distributor.

with that generation of vehicle, the ignition system will operate without help from the computer. don't even troubleshoot the guts of the distributor, if you change the cap, rotor, and anything else, it will be the same price as a remanufactured distributor, and might not fix the problem. if you troubleshoot a low volrage related issue (no pulses, shorted or open circuit, unstable timing, etc), change the whole thing.

If this is a conversion from old points style to HEI modern style, the problem may be the resistance wire is still in the circuit, which should have been removed from the power circuit to the distributor.
If the ignition coil reads 12 volts to its 12 volts terminal, then you should replace the ignition module, furthermore, a pickup coil and sprocket can also be replaced from under the rotor but the distributor needs to be removed and disassembled to get to the pickup coil and sprocket. Some Fords don't need to be removed but do need some disassembling to replace all of its electrical components.

check spark with hei spark plug tool at cylinder wire and the coil itself at distributor if no spark
check rotor and cap for crack ,defect, bad terminal
check for current at coil and distributor

I owned a similar 1986 caddy

12 Volts on pink wire to dist with key on

The top of the cap is the HEI Ignition Coil

Inside dist is the pickup coil (no crank sensor)
& ignition module with the 3 or 4 wires

Maybe the module failed- if you have no spark
at plug wires

Sounds like you replaced alot of parts for nothing.
The pickup coil in the distributor "fires" the module which grounds the coil and the injectors.
Those components would need to be tested. The coil fires the plugs when the ground is removed by the module or the key switch.

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.

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.

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.

Fig. Fig. 3: Pick-up coil testing

HEI distributor and burning coils,it in you connection first make sure you install primary and secondary prorperly as it comes out of the cap , and inside the cap wire from modules dont make contact if you are burning its from primary circuit, this is the (B+) or (battery most likely), your secondary is your tach and that need to switch from postitive to negative for it to create spark obvously if tach was grounded or applied power you wont start,but there are times the condensor in the distributor does stays fixed and shorts out the coil (replace that condensor its for suppression) when the condensor is replaced run a fused direct wire at B+ (from ignition) run the vehicle and monitor the tach wire and check to see if that get hot

How about the MAP SENSOR? Do you check it out?

Hey , just take the positive wire from the coil you are removing and feed it to the + terminal on the HEI dist. cap.the other terminal under there is for your tachometer. If you are mounting a master kill switch in the bumper for drag racing- attatch the kill wire to the tach terminal also.
Thats it you just plug the three wire pigtail from the dist. base(pickup) to the cap and you are off.
Remember firing order is 18436572 in a clockwise direction. to find #1 remove #1 plug and have someone"bump" the engine over while holding your finger over the hole-carefull. then line up the slotted mark on the crank pulley with the big notch on the timing indicator. Good luck