Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Distributor Signal
To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: fuel quantity and quality, ignition system damage, cracks, moisture, etc., engine mechanical conditions such as valves, timing belt, etc. Also included are starter and battery circuit problems.
- Spark At Coil Check. Connect the spark tester between the ignition coil secondary wire and ground. Crank the engine. If a spark appears on the tester, go to step 2. If no spark appears, go to step 3.
- IDM To ECA Check. Install the breakout box. Connect test light between the breakout box Pin No. 47 and ground. Crank the engine. If the light flashes, replace the ECA. If the light does not flash, service the White wire from the ignition coil to the ECA.
- IDM At Coil Negative Terminal Check. Disconnect the ignition coil Yellow/Green wire. Connect test light between battery positive and the Yellow/Green wire. Crank the engine. If the light flashes, go to step 6. If the light does not flash, go to step 4.
- IDM From Distributor Check. Disconnect White wire from distributor connector. Connect test light Connect test light between battery positive and the White wire. Crank the engine. If the light flashes, service the wire from the distributor to the ignition coil. If the light does not flash, go to step 5.
- Power To Distributor Check. Measure voltage between distributor Black wire and ground. With the ignition key in the "OFF" position, zero volts should be displayed. With the key in the "ON" position, there should be more than 10 volts displayed. With the engine cranking, there should be more than 8.5 volts displayed. If voltage readings are correct, see SPARK above. If voltages are not to specification, perform TEST FC - VEHICLE POWER in appropriate G - TEST W/CODES article.
- Power To Coil (+) Check. Measure voltage between ignition coil (+) (Black wire for EFI, Black/White wire for Carb.) and ground. With the ignition key in the "OFF" position, zero volts should be displayed. With the key in the "ON" position, there should be more than 10 volts displayed. With the engine cranking, there should be more than 8.5 volts displayed. If voltage readings are correct, ignition coil is faulty and must be replaced. If voltages are not to specification, perform TEST FC - VEHICLE POWER in appropriate G - TEST W/CODES article. If TEST FC - VEHICLE POWER is okay, replace wire from ignition switch to coil.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.