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Coil On Plug Test

New 01/28/2005

Welcome back. My COP hurts when I cough. What should I do?

Jim
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Thanks for the welcome.

I just had a COP or Coil Per Plug (CPP) as it is officially know, fail completely. No doubt it was missing.

Took some readings and the primary side read 8 ohms and the primary to secondary around 5k ohms. Looking into this further I found the following:

coil pin B+ to the coil spring, 4K and 10K ohms
coil pin Coil Driver (primary ground) to coil pin B+, 0.3 and 0.8 ohms.

So the coil was for sure bad. Put it on a fast cycling SS relay at work and soon had smoke coming out of it. So I sawed it in half to see what was inside one of these little jewels and can say it is mostly epoxy. If the coil were to be shorting through the case it is at the bottom on the back side of it where the iron core is closest to the valve cover.

Here's a couple of pictures of the innards.

The two brass parts at the top are the pins for the primary input. At the bottom is a brass tab, that is cut off, where the spring attaches and is the secondary output.




The shiny center point is actually the iron core.

Here is the official Ford test procedure for the CPPs on out cars. Found out too that Ford made some of their other coils with reverse polarity for the primary input. The coils are marked B+ on the 12V + pin.

Here is the official test procedure enclosed in the Word Doc. Funny too that the usual P301-308 codes one gets when dealing with coil failure deal with fuel issues. The actual coil failure codes are P351-358 which did not show up for me.

Paul Nimz
 

JF1 PRELIMINARY CHECKS ON COIL, PLUGS AND BOOTS

Note: Electronic Ignition engine timing is entirely controlled by the PCM. Electronic Ignition engine timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.

• Continuous Memory Diagnostic Trouble Code (DTC) P0350 indicates an ignition coil primary circuit malfunction. Continuous Memory DTCs P0351, P0352, P0353, P0354, P0355, P0356, P0357, P0358, P0359 and P0360 indicate an ignition coil primary circuit malfunction has occurred in coils 1 through 10.
• Check all accessible coils and coil boots for insulation damage, looseness, shorting or other damage.
• Remove and check accessible spark plugs for damage, wear, carbon deposits and proper plug gap.
• Examine all wiring harnesses and connectors for damaged, burned or overheated insulation, damaged pins and loose or broken conditions.

Are coils, spark plugs and harnesses OK?

JF2 CHECK COIL RESISTANCE FROM COIL PINS TO SPRING TERMINAL

• Key off.
• Remove coil corresponding to misfire DTC.
• Check resistance from coil pin Coil Driver (CD) to the coil spring and from the coil pin B+ to the coil spring.

Are both resistances between 4K and 10K ohms?

JF3 CHECK COIL RESISTANCE BETWEEN COIL PINS

• Check resistance from coil pin CD to coil pin B+ of suspect cylinder(s).

Is resistance between 0.3 and 0.8 ohms?

JF4 CHECK COIL DRIVER LINE RESISTANCE

• Key off.
• Disconnect PCM. Inspect for damaged or pushed out pins, corrosion and loose wires. Service as necessary.
• Measure resistance from coil driver (CD) pin at PCM vehicle harness connector to CD pin at coil harness connector of suspect cylinder(s).

Is resistance less than 5 ohms?

JF5 CHECK COIL B+ LINE RESISTANCE

• PCM disconnected.
• Key on, engine off.
• Measure voltage between B+ at coil harness of suspect cylinder(s) and GND of suspect cylinder(s).

Is voltage greater than 10 volts?

JF6 CHECK FOR COIL DTCs P0351, P0352, P0353, P0354, P0355, P0356, P0357, P0358, P0359 or P0360

Is any coil DTC P0351 through P0360 present in Continuous Memory?

JF7 CHECK FOR DTC P0340 AND P0350

Is DTC P0340 present along with DTC P0350 in Continuous Memory?

JF8 CYLINDER COIL FAULT. CHECK FOR POWER TO THE COIL

· Key off.

· Install Electronic Ignition (EI) System Adapter (EDIS Systems Adapter) to 60-pin breakout box.

· Install Coil/CKP connector (black) to the coil and the harness connector (green) to the harness identified by the Continuous Memory DTC (example: P0356 is cylinder 6).

· Connect EI diagnostic negative lead to battery negative post.

· Use Integrated Electronic Ignition Coil On Plug overlay (Rotunda T97L-50-A2 or equivalent).

· Set EI harness type switch to 8 cylinder position.

· Key on, engine off.

· When making voltage checks, a ground reading means any value within a range of 0 to 1 volt. Also VPWR or COIL PWR readings mean any value that falls within a range of B+ to 2 volts less than B+.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J32 (COIL-) at the EI breakout box.

· 3.4/4.6L: J31 (COIL+) at the EI breakout box.

Is DC voltage reading greater than 10.0 volts?

JF9 CHECK FOR COIL HIGH AT COIL

· Key on, engine off.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

Is dc voltage reading greater than 10.0 volts?

JF10 CHECK FOR COIL HIGH AT PCM

· Key on, engine off.

· Measure voltage between J7 (B-) at the EI breakout box and the 104 pin breakout box Test Pin number identified in the following chart according to engine cylinder number:

·

 

·  

Is dc voltage reading greater than 10.0 volts?

JF11 CHECK FOR COIL LOW AT COIL CONNECTOR

· Key off.

· Disconnect coil from Coil/CKP connector, leave EI diagnostic harness connected to vehicle harness.

· Key on, engine off.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

Is dc voltage reading less than 0.5 volts?

JF12 CHECK COIL AT COIL CONNECTOR WHILE CRANKING

· Coil disconnected from EI diagnostic harness. EI diagnostic harness connected to vehicle harness.

· Connect EI diagnostic harness positive lead to battery.

· Connect an incandescent test lamp between J1 (B+) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

· Crank engine.

Does lamp blink consistently and brightly, one blink per engine revolution?

JF13 CHECK FOR COIL SHORT LOW

· Key off.

· Disconnect coil from Coil/CKP connector, leave EI diagnostic harness connected to vehicle harness coil connector.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

Is the resistance reading less than 2K ohms?

JF14 CHECK FOR COIL SHORT LOW IN PCM

· Key off.

· Coil disconnected from EI diagnostic harness. EI diagnostic harness connected to vehicle harness.

· Disconnect PCM from vehicle harness.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

Is the resistance reading greater than 10K ohms?

JF15 CHECK FOR COIL SHORT HIGH

· Key off.

· Coil disconnected from EI diagnostic harness. EI diagnostic harness connected to vehicle harness.

· Disconnect PCM from vehicle harness.

· Measure voltage between J7 (B-) at the EI breakout box and

· 5.4/6.8L: J31 (COIL+) at the EI breakout box.

· 3.4/4.6L: J32 (COIL-) at the EI breakout box.

Is dc voltage reading less than 0.5 volt?

JF20 DTC P0351, P0356 AND P0357: CRANKSHAFT POSITION SENSOR FAILURE

Are any of the above listed DTCs present?

JF21 CHECK RESISTANCE OF CRANKSHAFT POSITION SENSOR

· Measure resistance of Crankshaft Position Sensor.

Is resistance between 290 and 390 ohms?

HD40 CHECK CMP SENSOR OUTPUT

Diagnostic Trouble Code (DTC) P1309 indicates Misfire Detection Monitor is not enabled.

· Key off.

· Breakout box installed, PCM disconnected.

· Connect digital multimeter between Test Pin 85 (CMP) and Test Pins 51 or 103 (PWR GND) at the breakout box.

· Bump engine in short burst with the starter without starting engine for at least 10 engine revolutions.

Does digital multimeter reading switch between low (less than 2.0 volts DC) and high (greater than 8.0 volts DC)?

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Bet your'e glad you made that wisecrack to Paul eh Jim???

U.L.

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