Confused about ignition wiring test results

[haydeon]

I'm confused. Can anyone explain this?

I had no spark on my 1990 Civic. I did the coil and igniter tests in the FSM. I didn't have continuity on my white wire and blue wire (steps 5 and 6 in the Igniter Unit Input Test).

I finally just replaced both the igniter and coil, and the car started.

BUT I never found continuity in the blue or white wires.

Shouldn't the motor fail to start without continuity there?

 

[RonJ]

Describe exactly how you did the continuity test. Also post a picture of your multimeter.

 

[haydeon]

Describe exactly how you did the continuity test. Also post a picture of your multimeter.

• I took off the distributor cap.
• Pulled the little plastic cover and the rotor.
• Unplugged the wires. Some wires were different colors than listed in the FSM.

black = white
black/yellow = black/yellow
orange/blue = white/blue
blue = blue​

• Checked for voltage on the two-colored wires by touching red probe to wire end and black end to ground. Found proper voltage there. It was 11 point something. A little low from trying to start it over and over.
• Checked for continuity on the other two wires by setting multimeter to beep for continuity. Toched red probe to wire end and black probe to ground. No beep. No continuity. I tried this multiple times using various ground locations and with the key both on and off.

 

[RonJ]

Checked for continuity on the other two wires by setting multimeter to beep for continuity. Toched red probe to wire end and black probe to ground. No beep. No continuity. I tried this multiple times using various ground locations and with the key both on and off.

The problem is the way you did your "continuity" test. You were actually testing for a short to ground, not continuity.

Continuity test --> Touch the red meter probe to one end of a wire and the black meter probe to the other end of the same wire (continuity = beep sound).

 

[haydeon]

The problem is the way you did your "continuity" test. You were actually testing for a short to ground, not continuity.

Continuity test --> Touch the red meter probe to one end of a wire and the black meter probe to the other end of the same wire (continuity = beep sound).

You can also test for continity between a wire end and where it's grounded.

The FSM Igniter Unit Input Test that I posted says on #5 and #6:
"Check for continuity between the WHT wire and the body ground."
"Check for continuity between the BLU wire and the body ground."

Am I missing something in the terminology they're using? I understand how continuity works, and I think I have a basic understanding of what's going on with the ignitor. There are two wires coming in with voltage and two wires going out that should lead to ground. I think that's why it says to test for continuity between the wire and ground.

THEN if you don't have continuity to ground on each of those wires, it tells you to test for "open" (which I think means an open circuit) from the dizzy end of the wires and either the ECU or the tachometer ends of each wire.

Either way, I got it started. I would have gotten it done a lot faster if I hadn't followed the FSM in this case.

 

[RonJ]

You can also test for continity between a wire end and where it's grounded.

The FSM Igniter Unit Input Test that I posted says on #5 and #6:
"Check for continuity between the WHT wire and the body ground."
"Check for continuity between the BLU wire and the body ground."

These^ two tests are to detect continuity to body ground (= a short = a problem).

Am I missing something in the terminology they're using? I understand how continuity works, and I think I have a basic understanding of what's going on with the ignitor. There are two wires coming in with voltage and two wires going out that should lead to ground. I think that's why it says to test for continuity between the wire and ground.

Yes, you are missing the fact that reading continuity to body ground (a short) detects an abnormality, not a normal condition.

THEN if you don't have continuity to ground on each of those wires, it tells you to test for "open" (which I think means an open circuit) from the dizzy end of the wires and either the ECU or the tachometer ends of each wire.

Continuity to body ground indicates a short (outcome = bad).

No continuity to body ground indicates no short (outcome = good).

End-to-end continuity of a wire indicates the absence of an open/broken wire (outcome = good)

No end-to-end continuity of a wire indicates an open/broken wire (outcome = bad)

 

[haydeon]

These^ two tests are to detect continuity to body ground (= a short = a problem).

Yes, you are missing the fact that reading continuity to body ground (a short) detects an abnormality, not a normal condition.

Continuity to body ground indicates a short (outcome = bad).

Well, whoever wrote that section of the manual needs some help with English. On both of those tests it says "There should be continuity" which sounds like continuity is good.

You must be right though because the car is running!

 

[RonJ]

Well, whoever wrote that section of the manual needs some help with English. On both of those tests it says "There should be continuity" which sounds like continuity is good.

You must be right though because the car is running!

Well, Honda is a Japanese company. The written English in their service manuals is certainly not perfect, but it's generally adequate.

Edit:

I looked at the text (below) that you mentioned and, based on my knowledge of the system, the instructions are wrong.

These errors were corrected in the 6th generation Civic service manual:

 

[haydeon]

I looked at the text (below) that you mentioned and, based on my knowledge of the system, the instructions are wrong.

These errors were corrected in the 6th generation Civic service manual:

AH HA! Thank you for taking the time to look that up! I feel much better now.

 

[RonJ]

AH HA! Thank you for taking the time to look that up! I feel much better now.

 

[XpL0d3r]

RonJ, proving Honda wrong about their own cars since 1948.

 

[RonJ]

RonJ, proving Honda wrong about their own cars since 1948.

I'm not that good. Honda gets it right much more often than they get it wrong. Those errors in the 4th generation Civic manual are simply typos.

 

[mymmeryloss]

Ahhh vewwy guuuuuuuuud!