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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4644
Experience:  30+ Yrs of auto experience, Award Winning Svc. Manager; Just Answer Customer's Choice Award Winner
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How do I test ignition coils

Customer Question

How do I test ignition coils
Submitted: 4 months ago.
Category: Toyota
Expert:  Cary York replied 4 months ago.

Hi, I’m Cary and I’ll be helping you today.
Please understand that I can't smell, hear, or touch the vehicle, so patience is appreciated. Before leaving the site make sure and leave me a rating. You can still reply to me as many times as needed, even after the rating..

Do you have a volt/ohm meter?

Customer: replied 4 months ago.
Customer: replied 4 months ago.
Yea I have a DMM
Expert:  Cary York replied 4 months ago.

I was looking for a test procedure using an ohm meter but there is not one. What type of problem are you trying to diag.?

Customer: replied 4 months ago.
If the coil is bad
Customer: replied 4 months ago.
Coils*
Expert:  Cary York replied 4 months ago.

Do you have an engine misfire?

Customer: replied 4 months ago.
I do
Expert:  Cary York replied 4 months ago.

Well I can help diag. Do you have a check engine light?

Expert:  Cary York replied 4 months ago.

To help better serve you and give you accurate repair help we need to talk. Its not just one phone call. We can call back several times if needed till the problem is solved.

Customer: replied 4 months ago.
Can afford phone call atm but yes it does have misfire and the check engine light is on.
Expert:  Toyota Service replied 4 months ago.

Hello. Different expert here. The test for the coils is to see if you have specific voltage at the wire connectors of the coils. Is your meter capable of reading DC volts?

Customer: replied 4 months ago.
I does read DC volts.
Expert:  Toyota Service replied 4 months ago.

Can you do a few voltage tests at the moment?

Customer: replied 4 months ago.
In about an hour I can at Nissan working atm
Expert:  Toyota Service replied 4 months ago.

Ok. Please rejoin the conversation when you are ready. We will need to measure the voltages at the coil wire connectors. If the voltages are correct the coil or coils can be understood as faulty. There is no "ohm" test for the individual coils, as a resistance value is not part of the operation of the coils.

Customer: replied 4 months ago.
Ok thank you ��
Expert:  Toyota Service replied 4 months ago.

You are very welcome.

Customer: replied 4 months ago.
I'm around Toyota right now.
Customer: replied 4 months ago.
I have connector unplug from coil how test for voltage.
Expert:  Toyota Service replied 4 months ago.

Please advise of the colors of the wires so I know whch connector you have unplugged

Customer: replied 4 months ago.
Blk/wh, yel/blk,blk, and blk/wh
Expert:  Toyota Service replied 4 months ago.

Key On. Test for power in the black/white wire please.

Expert:  Toyota Service replied 4 months ago.

thanks

Expert:  Toyota Service replied 4 months ago.

Then test for voltage on the black/yellow wire.

Customer: replied 4 months ago.
I got 12v for black/white wire and 5v for yellow
Expert:  Toyota Service replied 4 months ago.

good

Expert:  Toyota Service replied 4 months ago.

All of the black/yellow wires should measure the same on each connector

Expert:  Toyota Service replied 4 months ago.

All of the black/white wires should measure the same.

Customer: replied 4 months ago.
does that mean the coils are junk and all wires are the same volts
Expert:  Toyota Service replied 4 months ago.

The following wires (one in each of the 6 connectors) should measure up to 4.5 volts:

Green

Black/Red

Green/black

Blue/Yellow

Blue

Light green

If all the voltages in all the connectors pass the voltage test, I would start to replace coils. Note: NON-Toyota coils are notorious for causing cylinder misfires. If you had a code reader, determine which cylinder is misfiring. Let's say you get a P0302 code (cylinder 2) Swap that coil with cylinder 4 and clear the code. Start it up and wait for the check engine light to come on again. If you get a P0304 (cylinder 4), the coil that moved from cyl 2 to cyl 4 is bad.

Expert:  Toyota Service replied 4 months ago.

Personally, if the coils are original, or not Genuine Toyota parts, I would replace all 6

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