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View Full Version : Bad IRCM? - Lets try this forum..



HwyStar
09-19-2013, 08:05 PM
I saw a recent post on someone having a problem with their IRCM, but didnt want to hijack. Tried this in the subscriber forums, and you could hear the crickets.

Anyway, I have a fuel pump intermittently starting on its own with the ignition key off. I put the breakout box on after finding that there was a difference in voltage between verified good grounds to the computer and pin 22 T/LG from the EEC. Pin 22 is used to ground the fp relay to energize fp. Im seeing 1.07v difference. If this was a straight switching ground, wouldnt I see no difference in voltage, or something like 300mV or less as Ford suggests? Im not sure if this is really that big of a problem. I put the BOB on to eliminate the rest of the harness, and Im seeing exactly that difference still. Bad computer??
http://www.spaceship.com/~windstarpro/Pictures/Cougar/diffvolts.jpg

However, after seeing that, I saw that there was voltage there with the ignition key off constantly. Checked the other side of the relay, and voltage there too. Ok, checked START/RUN pins at the BOB, and had voltage there too. ~~~? This thing does turn off when the key is off, but those two pins still have power. Follow that back and it goes to the IRCM, and Iam getting voltage there with the key off, and no voltage in at pin 13 on IRCM. So, am I correct in assuming the IRCM is fragged with internal relay stuck shut? There isnt a description of operation on the IRCM in the books I have, and Im not sure how that relay is REALLY supposed to operate. The voltage inverter is a little confusing.

Seperatly I saw 0v reference voltage at pin 46 and the car would run like that. I figure I will verify no ref volts AT the sensors too. The other reference volts channel was fine at 5.03v. Starting to wonder...

mikedenton49
09-19-2013, 09:01 PM
Ricket ricket

Way over the heads buddy.

HwyStar
09-19-2013, 09:20 PM
Im sure someone has seen this before. Especially Ricardoa, or XR7 Dave. They eat this stuff.

I checked Ref voltage on Pin 26 and it was low at 4.98v. Its been my experience anything below 5v is a problem even when battery volts were 12.00. I checked Pin 46 ref volts and got nothing. Im sure thats why the car started hunting. So, in any case the computer is wasted. RockAuto has a SMP reman PCM for 165.00 That shows a oe number of FOPF-******-ALA which matches my PCM, but does not show catch code. Also, lists F0PZ12A650ALA is the oe number you are purchasing. Does this matter? I ask since I have to put my chip in it and want things to work, but it was burned for AOHO. Does it really matter?

It think the IRCM may have fragged the computer. The START/RUN power to the PCM from the IRCM stayed on regardless of pin 13 volts(IRCM side), or ignition switch position. Checked hots and grounds and found diff in voltages less than 300mV. So, it isnt hots and grounds. I came up with a IRCM from SMP p/n RCM17. Ford part number E9SZ12B577A is what is listed for this unit, while the one in my car is E9SF12B77AB. Are they interchangeable? Does it matter. Price is 136.00 with a 36.00 exchange on RockAuto btw.

rlong
09-25-2013, 10:36 PM
i have never had trouble with ircm. i would prob try fuel pump relay . one time my cooling fan would kick on for no reason at nite and drain the battery , i ran an extra gound wire from battery to fender an it never did it again. some of the older tbirds had a recall on the ignition switch maybe its fouling up

sam jones
09-27-2013, 12:22 AM
Good evening

I agree with rlong. I have not had your problem of key off/fuel pump on. I have had the intermittent engine crank but will not start problem. What made this unusual is the fan would also be intermittent. I cut wire #14 at the IRCM harness connector so the fan should be running with key on all the time. Then if by magic the problem would vanish. Car would start as if nothing happened. This happen for a month. Meanwhile I did more troubleshooting (fuel pressure, grounds and relays) and decided it was the IRCM (faulty eec relay). I changed 3 units. No fix. The same intermittent no start condition would happen again. So I unbolted the IRCM but left it connected to the harness. Turn the key on and started pulling/twisting/tapping the IRCM and harness The fan would intermittently start and stop. To make a long story short I used the year specific electrical schematic and the electrical vacuum troubleshooting manual found damaged wires at the harness leading to the IRCM. Open section of the harness and carefully repaired. Fix problem. Hopes this helps.

HwyStar
09-27-2013, 09:32 AM
Sounds like a rough time. Mine wasnt that tough. Turned out the IRCM was bad, and I believe it cooked the computer. I put the breakout box on the EEC and noticed the hot while cranking/run feeds to the EEC stayed on with key off. That comes from the IRCM. So, I checked volts in from ign switch. I was getting voltage when I was supposed to and the ground was good to the module. So, replaced IRCM with crusty one off of a wreck and that fixed that. I ended up replacing the computer too due to loss of reference voltage.

J dot Miller
09-28-2013, 10:24 AM
Interesting. Where did you get the breakout box?

HwyStar
09-28-2013, 12:04 PM
Cant remember who, but someone on this board was selling two at once. I bought one of them. It is a Thexton for EEC4.

J dot Miller
09-28-2013, 02:23 PM
This thread inspired me.

I have been dreaming of owning a breakout box for years... I was drooling at breakout boxes and stumbled on a Rotunda EEC-IV 60-Pin Breakout Box for $75. It was such a great deal I had to buy it. Not sure if I need to source accessories to check voltage and resistance... :eek:

Since I recently learned how to re-solder components on circuit boards and plan to try to rebuild a few ICRM's (among other things). I found a Ford Rotunda ICRM Tester #007-00050 cheap and purchased it too.

My 97 5.4L is going to be a daily driver once again and my 90 XR7 will be the show car. I will make her run as good as the 97... I will need to learn how to use my new toys.
:)

HwyStar
09-28-2013, 06:02 PM
No, don't need anything special to read stuff. Its got female pins you stick normal probes into. Real handy. All it is, is a feed off a jump connector between the computer and harness. Always use digital meter though for highest tester resistance. I also got the IRCM tester off ebay a couple days ago after dealing with the failure of one. Using these BOBs is nothing new for me. Used them for resistance checks on antennas and cables for 688s at my last command.

JT's03
09-28-2013, 07:40 PM
I need to get one of these. I'm sure mine is a 104 pin connector. I'm having some weird issues with my cars electrical system and I think one of these bob's would come in handy.

J dot Miller
09-28-2013, 07:49 PM
Depending on your year you may need an adapter? :confused:


No, don't need anything special to read stuff. Its got female pins you stick normal probes into. Real handy. All it is, is a feed off a jump connector between the computer and harness. Always use digital meter though for highest tester resistance. I also got the IRCM tester off ebay a couple days ago after dealing with the failure of one. Using these BOBs is nothing new for me. Used them for resistance checks on antennas and cables for 688s at my last command.

Great. I assume the voltage and resistance reference values are in the Ford shop manual.

HwyStar
09-28-2013, 08:26 PM
Actually, they make a seperate BOB for the late EEC. As far as voltages go, I think they are somewhere in there. I just use Snappy MODIS, has all the values in it. The MODIS also tells you easiest place to test. But, using the BOB means you dont have to crawl around under the dash and hood trying to back probe connectors. Makes things a lot easier.


http://www.ebay.com/bhp/ford-breakout-box
Quick search on ebay. Found that there is a Rotunda and a OTC. But, may same since OTC makes oe tools for Ford.