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Discussion Starter · #1 ·
Vehicle starts and runs. only codes are 157 and 212 in memory.

When i put the key in the ON position, you can hear very regular ticking and the tack will bounce to the tick.
under the hood the ticking is pretty loud and definitely from the coil.

pull the ignition wire and the sound still exists.
pull the two wire connector form the ignition coil and the sound stops

the radio condenser (capacitor) broke at the point where the wire connects so i disconnected it at the connector for the condenser (capacitor)

i have the black ICM.

I replaced the coil with a new Motorcraft F7PZ12029AA and no change.

It almost seems like the ICM is sending a PIP signal to the coil when the engine is not running.

Any Ideas on what's happening here?
 

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Try unplugging the ICM and see if the "ticking" goes away, that should tell you if the ICM is somehow the cause.
The ICM is functionally equivalent to the old breaker plate in a point type ignition system. The PIP signal causes the signal to the coil to be interrupted just as the old points in the point ignition system did when the points opened. Interrupting the coil signal causes the collapse of the magnetic field in the primary sided of the coil, inducing the high voltage signal to fire the spark plugs. The ICM provides the signal to drop the coil signal.
Stick a paperclip in the coil wire (at the distributor) and see if you are getting a spark that coincides with the coil "ticking".
 

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Yo 92broncoboy,
It's very good that you filled out your signature with MAF, etc, because I would've suggest you re-do the code test.

DTC 157 indicates the Mass Air Flow (MAF) sensor signal went below 0.4 volt sometime during the last 80 warm-up cycles.
Possible causes:
-- Poor continuity in MAF sensor harness or connectors.
-- Intermittent open or short in MAF sensor or harness.
-- Damaged MAF sensor.
-- Idle Air Control (IAC) system (possible closed throttle position indication).

MAF Wiring Diagram in a 95 (see#3) by SEABRONC

Clear Continuous Memory (refer to Quick Test Appendix, «Section 5A»).Start engine and idle for 5 to 10 minutes.
Run the throttle up to 1500 RPM for 10 seconds.
Key on, engine off.
Run Self-Test to observe Continuous Memory DTCs.
Is Continuous Memory DTC 157 present?
Yes
GO to «DC13».
No
GO to «DC11».

DC11 Monitor MAF Circuit under simulated road shock
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, reconnect PCM. (Breakout box is not absolutely necessary, it just provides easier access to the circuits for testing),
As I mentioned in another thread here; in place of the breakout box, go to the EEC pin instead; for instance - Measure resistance between Test Pin 33 and Test Pin 40, 46 and 60 at the breakout box. Substiture EEC for :breakout box"
EEC IV Connector Pin Diagram

by Ryan M (Fireguy50)

EEC IV Connector Pin LEGEND, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8;
Source: by Ryan M (Fireguy50) at http://web.archive.org/web/20120118104425/http://www.oldfuelinjection.com/truckpinouts.html

Connect DVOM between Test Pin 50 (SFI vehicles) or Test Pin 14 (MFI vehicles) and Test Pin 9 (SFI vehicles) or Test Pin 15 (MFI vehicles) at the breakout box.
Key on, engine running.
Lightly tap on MAF sensor and wiggle harness connector to simulate road shock.
NOTE:
MAF voltage is normally above 0.4 volt. A sudden decrease in this minimum limit indicates a fault.
Is a fault indicated?
Yes
DISCONNECT and INSPECT MAF sensor connector. If OK, REPLACE MAF sensor. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».
No
LEAVE DVOM and PCM connected. GO to «DC12».

DC12 Check harness for intermittent shorts and opens
Key on, engine off.
DVOM connected between Test Pin 50 (SFI vehicles) or Test Pin 14 (MFI vehicles) and Test Pin 9 (SFI vehicles) or Test Pin 15 (MFI vehicles) at the breakout box.
-- Grasp the vehicle harness closest to the MAF sensor connector. Shake and bend a small section of the vehicle harness while working toward the dash panel. Also wiggle, shake and bend the vehicle harness from the dash panel to the PCM.
Is a fault indicated?
Yes
ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, «Section 5A»). RERUN «Quick Test».


DTC 212 Loss of IDM input to PCM or SPOUT circuit grounded.
See if the Spark Output (SPOUT) connector circuit is good by running a piece of wire where the "shorting bar" plugs into tje connector is supposed to go. If that doesn't clear 212, inspect the wiring all the way back as far as you can.

"...IDM is a feedback signal generated by the ignition system and is monitored at pin #4 of the ECM. Its purpose is to diagnose missed ignition primary pulses at the time the ECM commands the Spout signal to fire the coil. Since it is used solely for diagnostic purposes, if this circuit is not operating properly, it will not affect vehicle driveability; & by Seattle FSB
The Ignition Diagnostic Monitor (IDM) signal is a diagnostic signal for the PCM to to verify a coil firing for each PIP signal. If an erratic or missing IDM signal is received, a Diagnostic Trouble Code (DTC 212) is set. An occasional IDM signal may not affect drivability, but can still throw a trouble code. As SigEpBlue has stated, check for an intermittent ground on the spOUT and/or IDM circuit. Also, ensure that you have the correct Ignition Control Module (ICM) and it is wired correctly to the PCM..." Miesk5 NOTE; use BLACK CCD Ignition Modules in 94-96 Broncos
Source: by SMP via SigEpBlue (Steve) & by Seattle FSB at FSB
See attached
154195


154196

154197

154198

154199

154200

154201
 

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Discussion Starter · #4 ·
Try unplugging the ICM and see if the "ticking" goes away, that should tell you if the ICM is somehow the cause.

Stick a paperclip in the coil wire (at the distributor) and see if you are getting a spark that coincides with the coil "ticking".
thanks Mikey350 - the ticking does go away when the ICM is unplugged. i placed an inline spark plug tester between the coil and the distributor and the light coincides with the ticking.

also, when the ticking does occur, the tach moves in sync with it - even though the engine is not running.
 

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Interesting - so the ICM is being "told" to generate the coil signal (Pin 5 of the ICM, circuit 11)
As this is a reproducible problem, try disconnecting the Spout connector. (Normal up the rest of the ignition system) Normally the Spout signal (ckt 929) is a signal to tell the ICM how much timing advance to apply. (That's why the circuit is opened when setting the base timing.)
Try a little troubleshooting, the PIP signal is generated by the Hall effect pickup inside the distributor sensing the gaps in the armature (the black thing with the slots). I suppose that there is a chance that the Hall effect sensor has failed in some manner and it is generating a signal even without the armature rotating. So, take the top off the distributor, take the two small screws that hold the armature and remove it. In the gap of the Hall effect (PIP) there is a magnet on one side, and the PIP pickup (Hall effect switch). Try putting the tip of a magnetized screwdriver in that gap. If the Hall effect switch is in some strange oscillation, changing that magnetic field should at least change the pulse rate of the ticking. While you're in there look for (and remove) any rust or crap in the distributor bowl.
What frequency is the "ticking", about the same speed as the turn signals (for example)?
Have you had the instrument panel apart recently? Did you do ANYTHING recently before this problem? Do you have a battery charger connected? Did you add an aftermarket tach?
The circuit 648 that exits the schematic below on the left side goes to the tach. I was trying to determine if the errant signal may be coming FROM the instrument panel if something got shorted to that circuit.
The tach "jumping" is because it is seeing the signal on circuit 648. The tach is a basic R-C circuit (resistor-capacitor) that is monitored by the tach, which is a basic meter movement. The signal charges the capacitor, the resistor bleeds off the charge, the meter reads the charge. More pulses causes the capacitor to charge higher, and the meter reads higher.
The schematic below is at:
1996 Ford Bronco '94 EVTM picture | SuperMotors.net




Good luck
 

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Discussion Starter · #6 ·
so here's something unexpected - i pulled the distributor to inspect and clean out and when i disconnected the distributor harness the coil went nuts with the ticking. the tach was reading about 500 RPM at that point.
i reconnected the distributor harness (distributor not stabbed in) and still ticking. i spun the rotor and the ticking stopped.

when the ticking occurs there was never a battery charger connected. i do not have an aftermarket tach installed.

going to try to recreate with the IP cluster disconnected.
 

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Discussion Starter · #7 ·
Still ticks with IP cluster disconnected.
 

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That is extremely interesting. If I understand you correctly, you pulled the distributor and when you disconnected the plug on the distributor, the "ticking" increased.
This indicates that the signal causing the ICM to fire the coil is NOT coming from the distributor. So, let's do a little more troubleshooting.
If I remember correctly the connector on the ICM is 8 flat pins. The last wire on one end of the connector is a Gy/O (Gray wire with orange stripe), that is the PIP signal input to the ICM. That signal usually comes from the distributor, but you disconnected the distributor and something was still triggering the coil.
First shut off the ignition, then disconnect the distributor connector.
Next unplug the ICM and find the gray wire with the orange stripe (the last wire on the other end of the ICM connector is black, so it should be easy to tell which is which).
This next step is requires a bit of patience and skill. What I'd like you to do is prevent any signal from getting to the ICM on pin 1 by electrically insulating it from the socket. This will insulate ONLY the PIP signal and still allow the other signals to get to the ICM. Here's how I've done it.
Get a piece of paper (printer paper might work), maybe a post it note, or an inch of packing tape (Scotch tape MIGHT work, but it tears too easily). Cut a small strip of something the same width as the flat pin #1 on the ICM. Remember the object is to insulate the pin from connector, so fold the insulating material over both sides of the pin. Then put the connector back on the ICM.
Turn the ignition back on and see if the coil is still being triggered. If the ticking stops, the coil trigger signal is coming from the PCM or something shorted to the PIP signal (you disconnected the distributor, and that PIP signal (ck 395) should only be connected to the distributor and the PCM). The PCM should not be sending a signal without the PIP generating the pulses. You might need a new PCM.
If the "ticking" continues, disconnect the SPOUT to keep that signal from getting to the ICM through the normal route. Still ticking with the SPOUT plug disconnected?, tape off pin 2 of the ICM to see if some signal is leaking in on that pin.
Still ticking with pins 1 an 2 taped off?, tape off pin #3 (which is labeled "Start"). That signal comes from the PCM and I think it is just a "turn-on" signal to the ICM. We're trying to find a signal that is tricking the ICM into thinking it's getting a coil trigger signal. If pin #3 stops the ticking, the PCM is generating the signal and it shouldn't be.
Still ticking with pins 1, 2, and 3 taped off? This would indicate to me that the ICM is generating the coil trigger signal WITHOUT any input.
Just to make sure, tape off pin #5. This is the normal coil trigger signal.
If the coil is still being triggered with those four pins taped off (1,2,3 & 5), the signal is coming from SOMEWHERE but not from the ICM.
You could look at Splice 171 where the coil trigger signal splits to go to the dash and the coil. You'd have to untape the harness to see where the two wires diverge. That's why I asked earlier if you installed an aftermarket tach.
That coil trigger signal is coming from somewhere. hopefully the troubleshooting steps above will help you find its source.
Good Luck, and let me know the results of your testing.




1996 Ford Bronco '94 EVTM picture | SuperMotors.net
 

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Discussion Starter · #9 ·
thanks Mikey350
all of the below with the distributor disconnected
pulling pin 1 from the ICM - no change, still ticks
Pin 1 back in and SPOUT pulled - no more ticking

started to trace the wires between the ICM and PCM connector - clean - no abrasions or compromised wiring.
the SPOUT circuit does branch off somewhere else and this is what i'm digging into now.
slowly taking apart the harness to trace this
 

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Well, that shows some progress, the SPOUT signal somehow is causing the ICM to trigger the coil.
Taking apart the harness and tracing the pink SPOUT wire from the PCM to the SPOUT jumper might show something. The problem just might be the PCM.
Have you pulled the PCM and inspected it? I guess there could be some circuit that has somehow shorted itself to pin 36 on the PCM, leaking electrolytic capacitors on the PCM is a relatively common problem on these old Broncos. The electrolyte in the capacitors is conductive. (This is just a guess.)

As you converted to MAF from the old MAP (Speed Density) that was the original factory configuration, rechecking any PCM repinning you may have done could warrant a second look.
 

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Discussion Starter · #11 ·
thanks again @Mikey350 and @miesk5 - i can't run some of the tests with the breakout box which require the engine to be running since i don't have said box.
I'm pulling C101 and the PCM connector and going through all of the pinning again. unfortunately i haven't found any issues yet. hoping this might just be a bad few coils which just happens to show the correct primary and secondary resistances
 

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Yo 92,
As I mentioned in another thread here; in place of the breakout box, go to the EEC pin instead; for instance - Measure resistance between Test Pin 33 and Test Pin 40, 46 and 60 at the breakout box. Substiture EEC for :breakout box"
EEC IV Connector Pin Diagram



by Ryan M (Fireguy50)

EEC IV Connector Pin LEGEND, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8;
Source: by Ryan M (Fireguy50) at Ford Fuel Injection
And for DTC 212 again, "As SigEpBlue has stated, check for an intermittent ground on the spOUT and/or IDM circuit. Also, ensure that you have the correct Ignition Control Module (ICM) and it is wired correctly to the PCM..." Miesk5 NOTE; use BLACK CCD Ignition Modules in 94-96 Broncos"


Yo @Mikey350
Could TFI shielding combined with insulation break-down be part of the issue? Similar to
DTC) 211 TSB 95-15-11 for 93-95 (Shorts in Profile Ignition Pickup (PIP) & Spark Output (SPOUT)); "..The symptoms may occur during any drive mode or at idle. These concerns may be caused by the shielding drain wire (Circuit 48.) cutting through the insulation of, and shorting to, the Profile Ignition Pickup (PIP) wire (Circuit 395) or the spark output (SPOUT) wire (Circuit 929) near the Powertrain Control Module (PCM) 60-pin connector.
155435

A protruding wire from Splice 145 may also cause the same concern as the wire strand shorts to the PIP, SPOUT, or the foil wrap surrounding the drain wire...

"It seems that the insulation around many PIP sensors break-down prematurely - a condition that leads to shorting of the wires leading to the TFI ignition module"
 

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Discussion Starter · #13 ·
as odd as this might sound, i replaced the belt tensioner assembly and that smoothed out the idle significantly.
i installed an old Jacobs Ignition system that i had originally installed on the 302 that the truck was born with and the tick is gone.
i realize this is not diagnosing/troubleshooting but it helps getting rid of some of these odd symptoms to help focus on fixing other issues without confusing which symptoms/codes are related to which issues.

thanks @Mikey350 and @miesk5
 
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