No spark

[jmartin7]

89 with TFI-IV stopped suddenly after running for only a minute or so. Ran the previous day and before that with no problem. Now it won't start. Appears to be ignition problem.

Checked with test light at Tach terminal to ground per Haynes manual, and light flickers rapidly, (as mentioned in Bebop's posts), but does not appear to flash as Haynes suggests. What I'm seeing may be flashing, but that's not what I'd call it.

Anyway, no spark at coil. Coil resistance is supposed to be 0.3 to 1.0 ohm primary, and 8000 to 10000 ohm secondary. I get 0.53 primary and 7469 secondary. The secondary is a little low, but I'd normally not consider that bad. Is it bad based on those resistance readings?

This Bronco is kept outside, and had quite a bit of snow under the hood after a wicked lake effect snow storm with 30+ mph wind. This isn't the first time I've had a bunch of snow under the hood. but wonder if the snow is causing the problem. It didn't run long enough to warm up and melt any snow before it stalled, so it wouldn't have gotten wet.

I've never tried the self-test code readings. Might there be a code for this problem?

Any ideas? Thanks.

 

[miesk5]

89 with TFI-IV stopped suddenly after running for only a minute or so. Ran the previous day and before that with no problem. Now it won't start. Appears to be ignition problem.
Checked with test light at Tach terminal to ground per Haynes manual, and light flickers rapidly, (as mentioned in Bebop's posts), but does not appear to flash as Haynes suggests. What I'm seeing may be flashing, but that's not what I'd call it.

Anyway, no spark at coil. Coil resistance is supposed to be 0.3 to 1.0 ohm primary, and 8000 to 10000 ohm secondary. I get 0.53 primary and 7469 secondary. The secondary is a little low, but I'd normally not consider that bad. Is it bad based on those resistance readings?

This Bronco is kept outside, and had quite a bit of snow under the hood after a wicked lake effect snow storm with 30+ mph wind. This isn't the first time I've had a bunch of snow under the hood. but wonder if the snow is causing the problem. It didn't run long enough to warm up and melt any snow before it stalled, so it wouldn't have gotten wet.

I've never tried the self-test code readings. Might there be a code for this problem?

Any ideas? Thanks.

 

[miesk5]

J,

Check Batty Voltage; then try to start and test Voltage again (should be 13.5 - 14.5 volts while running)

Do the Self Test; prob just KOEO for now to see if you get a 2 digit DTC....

to do da KOER test, eng must be up to Normal Operating Tems, so hopefully a Code will pop-up in the KOEO phase.

Self Test for Diagnostic Trouble Codes (DTCs) by our Pal, BroncoJoe:

http://broncozone.com/forums/index.php?sho...amp;#entry74587

some possibilities are:

14 ECA detected an intermittent loss of the Profile Ignition Pick Up (PIP) signal.

18 Loss of Tach signal to the ECA.

19 Loss of power to the ECA during KOEO. If the vehicle is equipped with DIS then it could be failure of CID identification or camshaft input signal. Otherwise replace the ECA

Check batty Connections & all Grounds

 

[jmartin7]

I did the self test and got 21, 24, which Haynes says are sensor out of normal range. I suspect that's because the engine was not at normal temp as normally required for this test.

I also got 18, which is not in Haynes, but you suggest it's loss of Tach signal to the ECA. This code came in after the KOEO was done, and should be a "continuous code" according to Haynes.

Haynes also says those continuous codes come in after 40-80 driving cycles. Does that make sense, since the engine has been running fine and just shut down suddenly?

I think you're on to something, and I appreciate the help.

 

[miesk5]

I did the self test and got 21, 24, which Haynes says are sensor out of normal range. I suspect that's because the engine was not at normal temp as normally required for this test.
I also got 18, which is not in Haynes, but you suggest it's loss of Tach signal to the ECA. This code came in after the KOEO was done, and should be a "continuous code" according to Haynes.

Haynes also says those continuous codes come in after 40-80 driving cycles. Does that make sense, since the engine has been running fine and just shut down suddenly?

I think you're on to something, and I appreciate the help.

ok, have to go now so;

DTC 18

Loss of TACH signal from TFI (Thick Film Integration- the module on the side of the distributor) module to the PCM. There is an open in the SPOUT circuit. Suspect & Check da SPOUT connector.

Bad TFI, bad mag pickup, DIS bad coil

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[url="http://Hall%20Effect%20Sensor%20Overview%20&%20Diagram,%20Ford%20TFI;%20the%20Hall%20Effect%20Signal%20is%20called%20the%20

 

[regarrr]

I had a similar problem with my 87, minus the snow though. Can you hear your fuel pump kick on when you turn the key? If not, check the wires on the relay box mounted to the air filter box. There is a yellow wire that is vital for spark and fuel. If you can hear the fuel pump, make sure the White/Blue wire going from the coil to the ignition control module is good. Mine died out of the blue and that three way splice on the White/Blue wire was the problem. I just respliced it and everything worked fine again.

 

[regarrr]

Maybe this can help.

http://broncozone.com/forums/index.php?sho...amp;#entry84724

 

[jmartin7]

Fuel pump does come on. I'll look at that White/Blue wire, and I also plan on performing the PIP and PCM tests mentioned in Haynes related to the PIP and SPOUT signals based on Code 18 troubleshooting. Haynes did not list Code 18 in their list, but it is discussed in other sections.

I've popped the dist. cap off to make sure the rotor is spinning...and it is. Did not get a chance to thoroughly inspect anything else under the cap.

I've done the basic connector checks, looked for broken/loose wires...nothing that easy unfortunately.

I'll take any ideas and the voices of experience are very welcome. Thanks.

 

[jmartin7]

UPDATE:

Based on two recommended tests out of the many I performed, I determined the ICM must be bad. The two tests in particular were the AC voltage checks of the PIP and SPOUT signals at the ICM connector wires. Haynes suggested inserting a pin through the wire insulation to access the wiring, and that worked well enough. Both AC voltages were in range, and Haynes says that by process of elimination the ICM must be bad.

I purchased an ICM and rotor from Advance Auto since it was Christmas eve and NAPA and the Ford dealer were closed. I didn't have the luxury of time to wait since I needed this vehicle running ASAP. I would have liked to also replace the PIP sensor (aka Hall effect and pickup coil), but AA didn't have one in stock.

The truck fired up on the first crank, and all is well since then. I hope the brand-x parts hold up.

Incidentally, the resistance checks of the old ICM recommended in Haynes were all in spec, so I'm glad I did not rely only on that set of tests. Even though the resistance values were ok, the electronic function was not. That should be a word of caution for anyone else having to troubleshoot a similar problem.

Thanks to all for the help.