PCM problem please help

[skeeter72]

so after perusing the interwebs i found out a little more about the numbers on the eec. the f3ft-12b565-da number is the actual model number. according to this, http://www.thedieselstop.com/archives/ubbthreads/199497_4/showflat.php-Cat=&Number=1844381&page=92&view=collapsed&sb=5&o=&fpart=1.htm , the part number tells me my eec was originally developed in 93 and it has gone through a bunch of different generations. The new one i got was first manufactured in 94 and it is a first generation of its kind. the bigger font numbers are some sort of programming. however, both of my eec's have the number DPC-100 printed on them and according to the link it seems to carry some sort of weight. Any more help would be nice and possible ideas on previously asked questions would be greatly appreciated.

 

[ifrythings]

From what I understand your saying is everything works fine (transmission wise) and just the tach doesn't work, correct? If so, I would jumper the two wires and see if your tach does actually work or if the dealer just fed you a bunch of bs, I've seen a few of these tachs go dead in different ways (dead, needle pined, intermittent) and all that needed to be done to them was either pull them out of the instrument cluster and clean the 3-4 pins or re-solder the little circuit board on them and they work perfectly after. There's also a way to calibrate them using your computer or a signal generator, but I won't get into that one.

Also if you want to check the tach sensor, take it out of the truck, take a multimeter and put it on AC volts (20 volt or less setting) and put the sensor end (part that was in the engine) against a power adapter for some electronic thing in your house (you have to use the heavy ones, the transformer in it will make a alternating magnetic field that a working sensor will pick up and show on a multimeter) if the sensor is bad, you will get nothing from it, if good it will show some voltage up to several volts. P.S. electric motors should work too, they generate alternating magnetic fields.

 

[skeeter72]

Kinda of correct. I'm not sure what component is the culprit in this situation. About a week ago I got into my truck and started her up. The tachometer needle went up a couple 100 rpm and then does not register anything. My overdrive light says off. Now that I mention a couple years ago I had a similar situation with the tach not working but the overdrive off light would flash. The overdrive off light just remains on now. The situation a couple years ago was a bad connection between sensor according to the mechanic and he fixed. However now I have no clue what's wrong the dealership says it's the EEC but a remaned EEC in last night and still the same problem. However the remaned EEC had a different code on it and was a model year later than the one pulled out of the truck, but it is still an EEC for a 94 7.3 e40d. I will test the sensor tonight I have an xbox that was that big brick power supply adapter. Do you think that will work.


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[79jasper]

Only need 12 volts.

 

[ifrythings]

However the remaned EEC had a different code on it and was a model year later than the one pulled out of the truck, but it is still an EEC for a 94 7.3 e40d. I will test the sensor tonight I have an xbox that was that big brick power supply adapter. Do you think that will work.

I have heard that the newer eec's had improved programing for line pressure and shift scheduling, I believe you should have no problems using this one instead of your old one.

No the xbox brick power supply wont work, there a high frequency and very heavily shielded unit, it wont give off any magnetic fields, look for one of these that weight a few pounds (cell phone ones wont work too light , there like the xbox power bricks)

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[skeeter72]

Alright this is my official tach test. I could not find any heavy plug like the one
^^^^^ in the picture^^^^^^ above so I'm hoping my cordless tool charger battery will work. Here's the set up

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Here's what the multimeter is set to

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Let me know if you see any error in my ways


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[trackspeeder]

Ok a quick derail here.

All 89 through 94 E4OD equipped IDI's use a TCM. Transmission Control Module there is no engine control with this box

94.5 and up E4OD/4R100/5R110 ZF5/ZF6 use a PCM Powertrain Control Module. this box controls everything in the power train.

EEC and ECM are gasoline engine controls. You will find a plug labeled EEC on a IDI, but its a connection for the TCM. Ford makes this stuff fun.

When you go to a good dealer they will give you the correct name for the correct part to avoid confusion like this.

Ok the track crew will rerail this thread now.

 

[OLDBULL8]

http://www.autoecms.com/parts/Details.cfm?ProdID=1769631&ord=core 1994

http://www.autoecms.com/parts/Details.cfm?ProdID=1769041&ord=core 1993

http://www.autoecms.com/parts/Details.cfm?ProdID=1769636&ord=product_name

Here is El diagram may not be the same as 1994, see if wire colors match for the tach. I don't have a 94 diagram.

You cannot check for voltage on the tach hooked up. Take tach out, hook VOM to the leads on it set at the lowest scale on AC, swipe a iron metal piece past the end several times, should get a swing on the meter. Voltage will be in the Micro volts.

 

[ifrythings]

The pin outs for all of the TECA (TCM) for all E4OD's behind an idi are all the same, a few wire colors have changed here and there but they go to the same thing, they all should interchange with no problems (this statement does NOT include E4OD's from PSD's put behind an idi)

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88-89

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90-91

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92 and up

 

[ifrythings]

Alright this is my official tach test. I could not find any heavy plug like the one
^^^^^ in the picture^^^^^^ above so I'm hoping my cordless tool charger battery will work. Here's the set up

You must be registered for see images attach

Here's what the multimeter is set to

You must be registered for see images attach

Let me know if you see any error in my ways

I'm not sure if the 200v setting on your meter is going to work, try finding a meter with a lower scale for ac volts 2-20v should be ok as they will have a decimal point. I don't think your battery charger will work, but an automotive one will if you have one, I'm also going to see if an alternator on a running engine will work(damn curiosity sake lol)

Also check the resistance of the sensor, I'm not sure off hand what it should be but anywhere from a few kohms to 20 or so kohms should be alright, nothing means its toast.

P.s your meter does have 100's of millivolts (00.0) it may work but if you can get one that shows tenths (0.00) or hundredths (.000) would be best

 

[OLDBULL8]

DO NOT put any voltage to the sensor, it operates on the Halls effect, you will burn out the coil in it. By passing a piece of iron past the bottom, it collappes the magnetic field, then after the iron passes, it generates an AC signal. The resistance is around 2000 ohms.
Set the scale on 200Mv, The tach meter is nothing more than a volt meter, calibrated for RPM.

 

[skeeter72]

Alright I did everything said. I passed the sensor across every plug that looked like the picture in a previous post. Each plug I passed over I did multiple times on different settings. I also passed it over the handle of my cast iron skillet. DRUM ROLL........
......
.......
.......
Nothing. I got a zero reading every time. However I of think my voltmeter can't read the small if volts or it's just plain broke. The reason I think it might be the voltmeter is bc sometimes? I got the diodes crossed and passing over the skillet or a running hair dryer. The voltmeter would read zero but pop up a negative sign meaning it's reading something just not enough. We will find out when I get my new sensor in. Lastly, I fry things I love that diagram where is it from, it is the only one to have my true wire color scheme.


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[LCAM-01XA]

The F4 ('94) TCM/TECA/whateveryawannacallit is supposed to be the end-all-be-all control unit for the E4OD behind an IDI engine. They did some programming changes with it - IIRC base line pressure is bumped up by 10-15 psi in all gears, the line pressure while in OD now varies based on TPS readings instead of staying fixed regardless of throttle position, converter lockup in 2nd is disabled to avoid starving certain clutches for fluid, and shift points are slightly altered too. Thus replacing an older unit with a '94 one is considered an upgrade, and is actually recommended in certain situations. So it looks like your purchase got you the best factory control unit available for these trucks.

On testing the sensor, first thing I'd do is hook up one of the TCMs and with ignition on engine off check for voltage at the harness connector the tach sensor plugs into - one wire should have something (likely 5V), the other should be zero (ground). What I find interesting about the diagrams posted so far is they all show both wires for the tach sensor as hooked up to the TCM - which is exactly how my '90 EVTM shows them as well in the respective section of the book, BUT if one is to look in the instrument cluster section it will show one of the tach sensor wires (circuit #644) as constantly grounded. And indeed all that is required to bypass the TCM and bring the tachometer gauge back to life with the TCM powered down or removed is connecting circuit #648 (TCM pin #36) to circuit #11 (TCM pin #4) - there is no need whatsoever to touch circuit #644, wherever that wire wanders or branches off to between the tach sensor and TCM pin #44 it is enough to make the tach work even with the TCM completely disconnected from the harness. I know of at least two trucks that recently got converted from E4OD to stick that run their tachs just like that, circuits #648 and #11 jumped together and circuit #644 left alone as is - one truck has the TCM plugged into the harness but not powered up at all (relay is pulled) while the other truck has the TCM disconnected from the harness altogether and possibly removed from the truck. So if you're feeling adventurous you can copy the stickshift bypass and disconnect the harness from the TCM and jump harness pins #4 and #36 and fire up the truck on low idle and see if the tach reads what it should read (650-700 rpms)...

 

[ifrythings]

Alright I did everything said. I passed the sensor across every plug that looked like the picture in a previous post. Each plug I passed over I did multiple times on different settings. I also passed it over the handle of my cast iron skillet. DRUM ROLL........
......
.......
.......
Nothing. I got a zero reading every time. However I of think my voltmeter can't read the small if volts or it's just plain broke. The reason I think it might be the voltmeter is bc sometimes? I got the diodes crossed and passing over the skillet or a running hair dryer. The voltmeter would read zero but pop up a negative sign meaning it's reading something just not enough. We will find out when I get my new sensor in. Lastly, I fry things I love that diagram where is it from, it is the only one to have my true wire color scheme.

The 88-89 I found on here sometime ago, the other two are from what's left of my Haynes book after a flood. There are several versions of that book, the latest one (and most useless) has the bronco on the front, if you can find the one with a truck on the front, it will have that type of diagram in (well it'll have all 3 to be exact.

Back to your tach sensor, have you done a resistance check on it yet? If not, do one, should have some kind of resistance (around 2000 ohms thanks OLDBULL8).

P.s. when your meter is not connected to anything, they usually pop up the negative sign from internal drift, nothing you need to worry about in this situation, just ignore that it means nothing.

 

[trackspeeder]

The pin outs for all of the TECA (TCM) for all E4OD's behind an idi are all the same, a few wire colors have changed here and there but they go to the same thing, they all should interchange with no problems (this statement does NOT include E4OD's from PSD's put behind an idi)

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88-89

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90-91

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92 and up

This is why you can use any year TCM with the IDI. If you have a 89-91 E4 with brain issues. Replace it with a 94 model year. There will be some improvements in shift characteristics. The shift schedule wont suck so bad.