Sure Miss My '69

Recently bought this truck. It was running rough so I replaced distributor, rotor, plugs, and also has a brand new coil. Drove 50 miles, was running like a million bucks. On the 51st mile, the engine stopped like someone had pulled the plug. Bought a code scanner and got code 320: “Ignition/Dist Engine Speed Input Circuit Malfunction” then cleared all codes. Checked things over and discovered no spark. Got the Haynes manual out, ran through all the Haynes diagnostics and most everything checked out okay other than their error on the #4 pin on the ICM which is IDM out, not start. Had the ICM tested at O’Reilley’s and it tested okay but from what I’ve read posted here, that doesn’t necessarily mean anything. Everything seemed to check out okay but didn’t resolve the problem so I tried this link http://easyautodiagnostics.com/ford_...d_module_5.php
which was much more straightforward. I got to Test 7 to verify the signal from the PIP wire on the distributor to the #6 wire on the ICM. I was using a test light with the alligator clip on the positive battery terminal. With the key in the on position, I touched the tip of the test light to the pin I had stuck in the #6 ICM wire, and I heard various noises: one sounded like the fuel pump activating, the other sounded like it was coming from the distributor, and I think there were other noises in the engine compartment as well. I removed the test light and she fired up and was running like a charm. After 60 seconds, it quit again. Couldn’t restart it until I supplied power again to the #6 wire via the test light. Idled in the driveway for five minutes. Stopped and restarted 4 more times. Drove half a block and it quit. Supplied power again to the #6 ICM wire, heard the “reset” noises, put the tester away, and it started right up again. Scanned the codes again and came up with 320 again.

Does this sound more like the ICM needs replacing or the distributor stator/PIP sensor? Maybe an open/short somewhere which I haven't been able to locate?

Aktech

That is not what test 7 told you to do,in fact it tells you not to use a test light in lieu of a led set up. He even showed you what it looks like.

Sure Miss My '69

Hi Aktek, when it's 42 miles to town, you try the test lamp while you're waiting for the girlfriend to get back from town with the LED. The point is, while the bulb didn't light up, it did seem to reset whatever was causing the problem. Seems like an interesting point for helping diagnose the problem and might save someone else $50 on a tow truck.

Sure Miss My '69

Got my LED test light rigged up. Now, when the engine quits, I try to restart it right away and it just turns over. As soon as I hook up the LED test light between the positive terminal on the battery to the #6 wire on the ICM, it starts first time, every time. I don't hear the "resetting" noises like I hear when I use the test light, but the effect is the same. I don't understand how the PIP stator works or the ICM and haven't been able to find any detailed schematics, so not sure if this indicates a bad stator, bad ICM, or a short somewhere that is not allowing juice to get to the right place. When I test the #2 and #3 wires on the ICM I am getting 12v. Anybody??

Aktech

My book only goes to 95 so i`m not even going to look at it. Do you know what the specs are for pin #4? Pin 4 sounds like your problem. Why are u stuck on pin 6 if pin 4 is the problem. You need to do what the manual says to do. If u do what the manual says to do and it don`t pass the the test does ur manual tell what is bad? Ur manual should tell u how to test the pip and icm.

Sure Miss My '69

I have the 1996 version of the Haynes manual. On page 5-11 under "ICM Supply Voltage Check" #29 it says to "Turn ignition switch to start and measure for voltage this time at connector pin 4.” #33 goes on to say that voltage should be reading at least 90% of battery voltage. On most years, the Push TFI-IV module was used and the #4 wire on the ICM is Start. On mine (1996) I have the CCD TFI-IV module and the #4 wire is the Ignition Diagnostic Monitor and the schematic shows the wire going directly to the Powertrain Control Module. When I test for voltage, I get a fraction of a volt, less than one. The needle barely moves on my meter. Even this morning, when the engine is working fine and I have spark, the readings are the same. I am also getting 12v on the #2 and #3 wires as expected.


I am using the 7 diagnostic tests in the link in my first post. Everything checks out okay until I get to Test 7, “Testing the PIP Signal”. They list two possible outcomes, either the LED is flashing during the test in which case the culprit is the ICM, or the LED is not flashing during the test in which case the PIP stator is bad. The problem is that I am getting a third scenario: using the LED causes the engine to turn over and start running. If I run the LED from the + terminal of the battery to the #6 wire, the engine will start perfectly and run. If I run a test light from the + terminal to the #6 wire, I hear all kinds of “resetting” noises and then engine cranks over and runs. I’m guessing more voltage is getting through to the #6 wire when I use the test lamp. But I’m stumped as to why this is happening and whether the problem is the ICM, the PIP stator, holding my tongue on the wrong side of my mouth or something else. The grounds all seem to be fine and all the continuities check out so I don’t think there are any opens or shorts. Since I’m out of time for working on this, I’m going to bite the bullet and replace the distributor and the ICM and hope that fixes it.

kevinhun

hmm.. seems like a work for a professional.

Sure Miss My '69

I put in a new distributor and everything seems to be working fine now. I'd still like to know if anyone else with this problem can get their engine to start by using a test light between the + battery terminal and the #6 wire. Also found it was a pain in the backside to try to pierce wires with a needle so sticking the needle in the back of the plug where the wire enters works like a charm.

Aktech

Most of the time people are not going to do a unknown procedure. Test procedures are written in your book for a reason. Not doing a test right or not finishing the test will give you the wrong results. I think you got lucky and didn`t fry the computer or burn some thing else up. And sticking your needle in the back of the plug is called back probing.