Second, if you're using a voltmeter, you'll see a series of very fast pulses go by- they may register a volt or two. These are the "fast codes" that the real STAR scan testers use, but they go by too fast (100x the normal scan rate) to be of any use to us. If you're watching the CE (Check Engine) light, you won't see anything.

Third, you'll get the on-demand codes- these indicate what the EEC box has found problems with _at the moment of the test_. They will be presented to you as either flashes of the CE light, or sweeps of the needle on the voltmeter. The code 21 would be presented as flash-flash, pause, flash. The on-demand codes will be presented twice- if the EEC-IV has found nothing wrong, it will give you code 11, twice: flash, pause, flash, longer pause, flash, pause, flash. The flashes and pauses for a given digit are each 1/2 second. The longer pause between digits are 4 seconds. The longer still pauses between codes are 6-9 seconds. If you'd like to see a code just to see what they look like, leave the trans in gear (MT) or drive (AT), or push in the clutch- and you'll get code 67 repeated twice. If there is more than one code detected, they will be presented in sequence, twice: 22, 47, 22, 47.

Fourth, you'll get the separator code. The Ford manuals call this code 10, but you can't see the _absence_ of a pulse for the 0- you'll just see a 6-to-9 second pause after the last "on-demand" code, then a single flash.

Fifth, you'll get the "continuous" codes- these are the codes that the EEC-IV has stored in its non-volatile memory from events that have occurred while you were driving in the past. Another 6-to-9 second pause after the separator code, and you'll get another sequence of 2-digit codes that will look exactly like the on-demand codes. If all is well, you'll once again see 11,11. So for example- if at some point in the past your throttle position sensor has wigged out while driving, you'll get a 23 in the continuous codes. If it's still wigged out at the time you start the test, you'll see it as a 23 in both the on-demand and continuous codes.

One last item is how to clear the continuous codes, so that you can see if new ones crop up. This is simply done by disconnecting and then reconnecting your jumper after all the tests have been run and the codes have been received. Pretty simple, _very_ powerful. Unquestionably your friend. Perhaps there's something to this computer stuff, after all.

To do the KOER test, set the car up as above. Then with the STI/signal return jumper disconnected, start up and run it at 2000 RPM or so for two minutes, to thoroughly warm up the EGO sensors and get everything stable. Shut down, reconnect the jumper, and immediately restart, and the EEC-IV will go into the KOER test. Several things will happen. The first is that you'll get the engine ID code- 2 pulses for a 4-cylinder, 3 pulses for a 6, and 4 for a V8. Then the EEC-IV will begin playing with its actuators and sensors, trying to fool them into going to the extremes of their ranges. During this interval the car will run very poorly at times- it may go rich, lean, stumble, buck, and do all manner of unpleasant things. This will last from 6 to 20 seconds. After this interval, the motor will smooth out and begin an even idle. You will then see a single flash or sweep of the needle. This is the Dynamic Response code, which is your cue. After this code, you have 10 seconds to snap the throttle wide open, just long enough to get above 2000 RPM. Once the engine gets above 2000 RPM (it won't take long at WOT with no load!), release the throttle, and let the engine go back to idle. This part is lovingly called the "goose test". The EEC-IV needs to see what happens at high throttle settings to make sure all of its sensors and actuators work properly, so you get to help out by goosing it. This test will last from 4-15 seconds. The goose test is followed by fast codes (which only those of us stuck with a meter will be able to see, and we can't do anything with them), followed by the KOER on-demand codes exactly as above. If all was well, you'll get 11-11. If you didn't goose it enough, you'll get a 77 and get to do it over again. At this point you can optionally run the SEFI or Cylinder Balance test. If you have an '87 or later, lightly tap the throttle (it only takes a small movement) WOT), and release it. Owners of '86s will have to go WOT briefly. After a little while, the EEC-IV will begin cutting the injector to each cylinder in turn, and looking for a drop in RPM. If there is no drop associated with any individual cylinder, then there is some problem there (that may or may not be related to the injection system- you could have a valve problem, or a fouled plug, or a shop towel stuck in the intake runner, and get the same effect). This test takes about 90 seconds. If a cylinder is found by this test to be weak, a single-digit code will be flashed telling you which one (1-8). If all is well, the code will be 9. If it gives you a 77, it got confused (perhaps you bumped the throttle) and you need to start over and rerun the test. '87 and later cars can then rerun the SEFI test after it finished, again by just tickling the throttle (saves having to go back through the whole KOER test). It also relaxes the criteria for "fail" with each retest, so if one cylinder fails the first time but passes the second, it's only a little weak- whereas if it fails 3 times in a row, it's profoundly dead. Those of us with '86s have to go back to Square 1 to rerun, and we don't get this progression of thresholds to help us troubleshoot.

11 - Normal...go out and drive with the blessings of the Mustang Gods!

12 (r): ECA could not increase idle speed above normal idle. Suspect throttle body coking. KE1

13 (r): ECA could not lower idle speed. Suspect Idle Bypass valve problems. KE15

14 (c): Intermittent PIP signal operation. Suspect PIP sensor or TFI module, or grounding or interference problems at the TFI module. Y1

15 (o): ECA ROM test failure- failure is internal to ECA. (c) ECA KAM (Keep Alive RAM Memory) failure. Q10

18 (r*): Loss of TACH signal from TFI (Thick Film Integration- the module on the side of the distributor) module to the ECA. There is an open in the SPOUT circuit. Suspect SPOUT connector. N1

19 (o): Failure of ECA voltage regulator. Replace ECA.

21 (or): ECT (Engine Coolant Temp) out of range. Coolant is less than 50degF for KOEO, or less than 180degF for KOER, or greater than 250degF for either. If coolant temp is in proper range, suspect ECT sensor (It won't be, for KOER tests on cars tha have a 160degF thermostat!) DE1, DE90

22 (orc*): MAP (Manifold Absolute Pressure, for speed-density cars) or BP (Barometric Pressure, for mass-air cars) sensor signal out of range. Suspect MAP or BP sensor and harness. DF1, DF90

23 (or): Closed throttle TP (Throttle Position) sensor voltage out of range. Suspect TP sensor. DH1

24 (or): ACT (Air Charge Temperature) sensor voltage out of range. Suspect ACT sensor and harness. 1984-85 2.3 Turbo - Vane Air Flow voltage out of range. DA1

25 (r): 2.3 Turbo. Knock Sensor failure. DG1

26 (or): VAF (Vane Air Flow, 2.3L Turbo) or MAF (Mass Air Flow) signal out of range. Suspect sensor and harness. DK1

28 (or): 1986+ 2.3 Turbo. Vane Air Temperature out of range.

34 (r): 2.3 Turbo. EGR On/Off not working. KA1

41 (c): 2.3 Turbo. EGO read lean for more than 15 seconds while in closed loop. HA11

42 (c): 2.3 Turbo. EGO read rich for more than 15 seconds while in closed loop. HA8

51 (orc*): ECT voltage too high (coolant too cold, circa -40degF!). Suspect ECT, harness. DE10, DE91

53 (orc*): TP sensor voltage too high (indicates WOT condition). DH3, DH90

54 (orc*): ACT (air Charge Temperature) sensor voltage too high. DA10, DA90

56 (orc*): MAF (VAF for 2.3 Turbo) sensor voltage too high. DK10, DK90

61 (orc*): ECT voltage too low- indicates coolant temp greater than 250degF.

63 (orc*): TP sensor voltage too low. DH10, DH94

64 (orc*): ACT (1984-84 2.3 Turbo, VAT) sensor voltage too low, indicates intake air temp greater than 250degF. DA20, DA93

66 (rc*): MAF (2.3 Turbo, VAF) below minimum test voltage. DK20, DK93

67 (o): Clutch switch open, AC left on, transmission in gear. FA1

68 (oc): 1986+ 2.3 Turbo. VAT out of range.

73 (r): Insufficient goose during Dynamic Response test. Rerun test, goose it harder. 2.3 Turbo - Faulty Throttle Position sensor. DH20

74 No Brake Switch Actuation / Cruise Control Switch Actuation Detected

76 (r): 2.3L Turbo only. Insufficient VAF variation seen during Dynamic Response test. DK30

77 (r): No goose detected durning Dynamic Respose test. Rerun test, goose it harder. M1

81 (o): 2.3 Turbo. Boost control circuit failure. KN1

82 (o): 2.3 Turbo. Check EDF signal to Integrated Controller for short to ground.

83 (o): 2.3L Turbo only. Check for EDF signal to Integrated Controller for open circuit.

84 (o): EVR solenoid circuit failure. 2.3 Turbo - Check for EGR solenoid open circuit.

85 (o): 2.3 Turbo with Automatic (T-Bird). Check for 3-4 shift solenoid open circuit.

87 (oc): FP relay circuit failure- suspect intertia switch, fusible link, FP relay. J1

98 (r): Hard fault present. The ECA is running in FMEM (Failure Effects Management Mode), so something is royally screwed up that the KOEO test should have told you about. Rerun KOEO and fix whatever you find there.

99: ECA hasn't learned yet

The smallblock Ford has come a long way in the last 30 years. In the simple "good old" days, the hot setup was a sizable Holley and a hot cam, and carburetion was set up with an eye on the plugs, an ear tuned for detonation, and a nose near the tailpipe. Many of us have whiled away a lot of pleasant hours this way over the years. And now we have come to a time when there is a bleeding computer in there! A computer that claims to understand how a motor is supposed to work, and that hides all the fun stuff from us. For those of us with late models, it seems like the fun is gone forever. Well, not really. This computer is what makes it possible to hang a Paxton on our cars with very little more than a couple of wrenches and a drill, and to set it up for good power without investing a set or two of melted-down pistons in the effort. It makes the thrash of rejetting the night before an event, in an effort to get the thing to run clean now that the new headers are installed, a thing of the past. And surprisingly, it makes the process of maintaining and troubleshooting all that federally-mandated pollution plumbing a relatively easy project. It turns out that the damned thing is our friend after all, especially once a few simple tricks are learned. Since I am well known as a hopeless computer weenie, and there's no way I'll ever be able to beat that rap, that's what this article is about. I was corresponding with a friend the other day, and he asked a good question. "I understand that the engine computer of the Mustang can be accessed, and that error codes can be obtained and looked up in the Ford manuals, but how are the codes accessed? Do you need some kind of computer? Is it difficult? I'm not really interested in tuning my engine right now, just in the error codes." Nope, it's not high-tech at all. You just need a piece of wire, and maybe a voltmeter if your car has no Check Engine light, and you can run the EEC-IV Quick Tests in the privacy of your own garage. These can give you an amazing wealth of information on the machine's health, without getting your knuckles dirty, and without pulling one plug or reaching for the leakdown tester. There are two tests you can do- the Key-On, Engine Off test (KOEO), and the Key-On, Engine Running (KOER).The two tests tell you different things, and each has its place. In order to run either test, the car has to be fully warmed up to operating temperature, and the car must be in neutral (both these steps are critical, or the only codes you will get will be the codes for "coolant too cold" and "transmission not in neutral"! Also make sure that the heater and A/C are off, or you'll get the code for "AC is on", which is the same as the code for "tranny not in neutral"... To run the tests, you must locate the EEC-IV test connectors. In the late model Mustang, these are in the engine compartment, right in front of the driver's side hood hinge. There are two connectors of interest- one is a 6-pin connector, and the other is a single pin connector. Both use 1/4" quick disconnect-style terminals, so you'll probably want to make yourself a jumper about 8" long with a 1/4" male QD terminal on each end, if you mean to do this often. Otherwise, any random chunk of wire will do.

Late Model Corner- the EEC-IV Self Test Error Codes Well, it's time to grab the bull by the tail and look at the situation headon. I'm going to try and paraphrase the EEC-IV selftest code dictionary, and get it online here. Now, note that the codes mean different things depending upon what model car you have- I'm going to do a very Mustang-specific thing and list only the meanings for 5.0L SEFI and SVO 2.3L Turbo applications. So you guys lurking here with the Escorts, pickup trucks, and SHOs may not find these definitions to your liking. Also, these codes are assembled from 4 different sources- the Ford service self-test code summary guide, the '86 H manual, the Watson book, and the little book that came with my blinky toy. And they don't always agree on what means what. So this rev 1.1 list may be subject to some change! My thanks to Dan Malek for his kind research into the codes for the 2.3L Turbo motors for the SVO. In these definitions, the EEC-IV is referred to as the ECA. It's not only good form, it's less to type. In parenthesis after the code itself will be flags for the tests during which it may occur: "o" for KOEO, "r" for KOER, and "c" for continuous or memory codes. Codes flagged with an asterisk will cause the MIL (Malfunction Indicator Light, better known as the Check Engine light) to come on. [ EMH - codes deleted ... see next posting ] Date: Thu, 24 Feb 94 18:12 PST From: uunet!veritas.com!sander (Sander Pool) Subject: revised EEC-IV list I spent some time going over the list of codes I sent yesterday. Some of 'em do not apply to our puppy so I took those out. I added the pinpoint tests that should be used to locate the fault. I have this list in my car so I can immediately lookup the error I might receive from my brand new check-light. -------- In parenthesis after the code itself will be flags for the tests during which it may occur: "o" for KOEO, "r" for KOER, and "c" for continuous or memory codes. Codes flagged with an asterisk will cause the MIL (Malfunction Indicator Light, better known as the Check Engine light) to come on.