EEC Wanted

[alanmassengale]

Computers getting harder to find than they used to be?
Put on a code reader for the first time in my 86, and ER codes are crazy, different every time. Thinking wiring broken down, but hoping a computer swap would fix it . (I'm lazy)

[MikeFleming]

Year of SVO, what letter ID EEC is in it now?

BTW - it's probably the wiring, IMHO. An there s always the PiMP alternative (but that also requires good wiring).

[alanmassengale]

'86, so I assume it's a PE. (I'm original owner)
Sorry I'm nooby, I wouldn't be sure where to start replacing wiring.
Don't even know what the PiMP is.
Maybe I should open the computer and inspect capacitors?

[majestic]

'86, so I assume it's a PE. (I'm original owner)
Sorry I'm nooby, I wouldn't be sure where to start replacing wiring.
Don't even know what the PiMP is.
Maybe I should open the computer and inspect capacitors?

If you decide you want to buy an EEC, I have a PE that we removed from our 86 SVO.

[alanmassengale]

Excellent thanks!
I think I'll start with checking and cleaning wiring, then looking at the inside of my computer, when the weather gets better.

[brsvo]

I am not sure but a few years back you could still get remaned ones from the parts stores. If they offer them get one and swap it in before you give them the core. If it doesn't work they may not take it back but you will have a spare. I gave my original back as a core and that was not the problem. Wasted a good PE.

[MikeFleming]

BTW - I have NEVER seen a bad capacitor inside a Ford EEC. The only failures I have seen are burned circuit board traces (almost certainly because someone shorted some inputs incorrectly) and dead output drivers (th9ngs that activate solenoids, injectors, etc.), Probably due to exceeding their rated load for too long.

Although there was one time I recall that an injector driver died (shorted with the injectors always on) . Shouldn't have been due to excessive load as those are current-regulated drivers.

[alanmassengale]

All great info, thanks much.
I still haven't taken it out and looked yet, but I think I'd like to pm you majestic, for a backup if nothing else.

[majestic]

All great info, thanks much.
I still haven't taken it out and looked yet, but I think I'd like to pm you majestic, for a backup if nothing else.
I’ll message you tomorrow. I’m away from my computer tonight.

[MikeFleming]

I’ll message you tomorrow. I’m away from my computer tonight. For "normal" folks, most all of the drinking / partying / carrying-on was the previous night. Just sayin'!

NOTE: I would never accuse an SVO owner of being "normal'.

[Laredo]

...Thinking wiring broken down, but hoping a computer swap would fix it . (I'm lazy)


...Maybe I should open the computer and inspect capacitors?

Replacing the ECM is last resort, and most likely NOT your problem.
In 5 years of working as dealership Ford tech back in the 90's, I replaced ZERO engine modules.
Odds are 99% you have a wiring / connection / activator / sensor / or mechanical problem.
Get yourself a DVOM and factory Ford Engine/Emissions manual and diagnose the problem, don't guess and needlessly replace expensive parts.
They have diagnostic flow charts to guide you to the problem source based on symptom and DTCs.
Some of the tests require a special "breakout box" but you can work around that.
If you need help to get through the tests, there's plenty available right here.

[KevinK]

I picked up a spare. Anyway to get them tested.

[alanmassengale]

Replacing the ECM is last resort, and most likely NOT your problem.
In 5 years of working as dealership Ford tech back in the 90's, I replaced ZERO engine modules.
Odds are 99% you have a wiring / connection / activator / sensor / or mechanical problem.
Get yourself a DVOM and factory Ford Engine/Emissions manual and diagnose the problem, don't guess and needlessly replace expensive parts.
They have diagnostic flow charts to guide you to the problem source based on symptom and DTCs.
Some of the tests require a special "breakout box" but you can work around that.
If you need help to get through the tests, there's plenty available right here.

Thanks for the advice, I will definitely look into those resources.
The reason I suspect the ECM more than that though is that electronics guys say the capacitors (like the ones that went out in my radio to kill the AM) are only designed to live about 25 years, and this is 2021 now.
I don't have much confidence in the codes I am getting now, since as I said, they keep changing, and some aren't even applicable to my car. Sounds like random crossed wires, so I'll try inspecting and cleaning/repair first.

[MikeFleming]

Post the codes. Let us have a think on them.

[Art Vandelay]

How does the car run?

[alanmassengale]

Runs very well... codes soon.

[Laredo]

You may also have an issue with that code reader. Do you have an analog sweep volt meter to check/confirm codes the "old fashioned" manual way?

[alanmassengale]

Well, now I have accomplished replacement of my fuel tank, pump, sending unit and filter. I had the injectors cleaned and one replaced, so wanted to make sure I wasn't just pumping any rust
from the original tank into the rail. (as well as getting rid of many more mud dauber nests!) That stuff was the first non-routine replacements ever on this 26k mile car.
It runs beautifully, and now only takes 1 crank to start, rather than 2-3 like before, so suspect original fuel pump was going out.
My main problem now is that my radiator fan still won't come on. The fan motor works if I jump it, and today I changed the fan controller relay, but that didn't help. The new relay looks like the same part, although it's stamped 9CB instead of 6BC like the original. I had checked the wiring as I could without taking stuff apart, and cleaned connections. So now I'm thinking I'll have to look into changed the temp sensor on the block. I'm really hoping I don't have to chase down the whole wiring trail. What's a DVOM?
Good news is that now my code reader gives a clean pass on KOEO, and only gives a 25 and 77 KOER, no knock sensed, and op error throttle wide open not detected. Those don't sound concerning to me. It may even be that I just don't floor the throttle quite long enough, cos I just hate to hear the engine race that high.
Now for that temp sensor...
I was trying to stay original, but new fan and controller could be unavoidable I guess.

[MikeFleming]

How hot is the engine getting when you're expecting the cooling fan to come on? The switch is 222 degrees F, iirc. Which is pretty toasty, but more than sufficient to keep a engine working with a proper cooling system.

DVOM - Digital Volt Ohm Meter. You can use one to test your coolant temp fan switch in a pan of boiling water (if you can get the water hot enough - maybe add some coolant to let it get to 230F. NOTE: Coolant is extremely toxic so be careful with it around pets, kids, spousal units, etc.). Use an IR thermometer to verify temps.

Code 25 and 77 are typical when the "Snap Test" is not performed properly. Or the engine isn't hot enough at the start of the test.

[alanmassengale]

It's amazing how either a new fuel pump or cleaning some wiring cleared up all the weird codes I was getting before- it was even telling me my engine was 5 and 7 and 8 cylinders!
Should I hold the pedal down a beat longer to get a good snap test? I just hate to rev it up so high.
So this coolant temp fan switch, correct me if I'm wrong, is on lower block or exhaust manifold, and is different from the coolant temp sensor/sender? Looks like replacement ones are cheap.

[alanmassengale]

It was getting to the top of the normal range on the dash gauge.
If a new temp switch doesn't fix it, I'm thinking I'll punt to an aftermarket controller.

[MikeFleming]

For the SNAP test:
When you get the signal, WOT (wide open throttle) immediately (Don't nurse it) - hold it on the floor and keep it there until at least 3000 RPM. The EEC wants to see more than 50% TPS signal AND more than 50% VAF movement. And it listens for knock during this portion of the test so if the head, valves, pistons, etc. aren't stinking hot, there won't be any pinging.

AS soon as it shows 3K on the tach, get off the throttle and let it come back to idle.

BTW - ALWAYS do the snap test from inside just like you're driving. In the rare case of the pedal or cable sticking on something, you're right there at the ignition switch to shut 'er down. BTW2 - The engine won't ever go past 6500 RPM where the EEC fuel cut-off is set.

Temp sensors:
On the upper part of the lower intake in the center between cylinders 3 & 3 is the CTS that feeds the EEC. Two wire sealed connector.

Back of the head on the driver side (LHD models) is the dash gauge temp sensor. Single stud, push-on connector. Below the oil pressure sensor can.

On the bottom of the lower intake ids the coolant passage. At the rear of that passage is the fan temp sensor. Find the coolant bypass hose that comes out of the manifold and goes t oone of the coolant tubes that feed the oil cooler to locate the fan temp sensor.

For 86 (and perhaps late 85) models the fan temp sensor is a two-wire connection. For earlier models it's a single stud, push-on like the gauge sensor.

The cooling fan temp switch is set to 222 F so if there is not a good, PRESSURIZED coolant system it will never come on as the unpressurized coolant will never get that hot. .That's usually the far right side of the temp gauge. A good way to test the system is, if you have AC, flip it on and the fan should come on.

[alanmassengale]

I don't know why the system wouldn't be well-pressurized, unless there is air in the system from my last flush.
Wow, so much great info. I'm blessed to have your help- you're a guru and a gentleman!

[alanmassengale]

I turned on the A/C switch, and the fan did not come on, but the A/C hasn't worked this century, so I don't know if that was a good test or not.
In my pic from below, then, the fan temp sensor is the white one with the black connector, to the left of the oil filter by the coolant hose? (not the black one further up) (connector off ignition module is?)
Also from below, I took a pic of my power steering reservoir. The hose is a cooling line? The ps fluid is the only fluid on the car never changed, so I'm looking for the easiest place to drain it.
Lastly, can you tell me what that third open connector to the left of the test connectors is?
Thanks so much.
100691007010071

[alanmassengale]

Well, I got the ps fluid changed, and decided to change the oil, even though it only has 600 miles on it, it is also over 10 years old. So now all fluids have been changed.
I was about to put the new filter on, when I noticed that what I think is the fan temp sensor might be a lot easier to take out while the oil filter is out of the way. But just getting the connector off was a real bear for me, and I'll have to look through my biggest, swiveled sockets I think to have a chance of getting it off, hopefully without breaking it or making a mess. And I just hope the part I got is the correct replacement, and will make the fan work.
10106

[MikeFleming]

Keep in mind that sensor goes into coolant - so you'd do yourself a big favor to drain the coolant and rinse the system with water first.

[alanmassengale]

Yes, been thinking about that. However, besides the fact that I just recently flushed the cooling system, that also would mean putting a new filter and oil back in/on, to start the engine, since I drained that and took off the filter partly just to get to the sensor (things are much harder on a put-together car just on jacks), then redraining oil/filter to get to it again!
Maybe I could just stick a plug or rag into the hole. Or catch most of it in a smallish container?

[MikeFleming]

Frst, drain and catch the coolant from the bottom of the radiator. You will only get abut half of the coolant volume as the block willstill have some coolant remaining. And hte lower parts of things (such as the coolant passage in the lower intake) will still ahve coolant in them.

Optional: Flush out all the remaining coolant with water. This means you will only have water dripping on you when you remove the temp switch. Otherwise you'll have *some* coolant drip on you. Which is sticky, gooey and toxic. Choose your poison. Once the switch is back in, replace the coolant. Flush coolant exposure with lots of fresh water. And do not allow pets near it.

T get access to the switch, take off the oil filter and catch the overflow. As long as the engine's not running, there won't be much dripping - it will stop soon. Optional: drain the filter and save the oil. When replacing the filter, add the captured oil back to the oil filler.. Or add fresh.

Be sure to top off coolant and oil as needed.

Open beer. Annotate in log / maintenance book.

[alanmassengale]

10108

Progress: Drained coolant, removed oil filter, removed fan switch/sensor, determined that I have the wrong new sensor (probably the gauge sending one), so ordered correct one, due here next week. Not really expecting it to fix the problem, as the old one still looked fine, low miles, ayk.
Meanwhile, I checked the old manual about fuses, and see that the fan circuit uses a 20 gauge fuseable link, near the starter motor relay. I guess it's one of the links coming out of the voltage regulator? How does one check that?
In another thread, others talked about installing a manual switch at the under-dash relay. I would like to bypass the relay to see if the problem is downstream, but not sure how to do that.
If neither of those things fixes the fan, I guess all that is left is to change the ECM, as I have a used backup, or just give in to the aftermarket fan controller. I'm not much of an electrician, so not into checking all wiring.
btw, what is the open connector coming off the harness running below the battery, near right edge of pic?
It's happy hour here, so she'll have to wait for next week to keep trying. :fi_av_smiles_y_17:

[Mike S]

The small connector near the battery is part of the code reader connections.

The ECM doesn't control the fan. The fan control sensor is located in the lower intake facing the firewall. The relay control for the fan is in the cabin just above your left knee. It is most likely your problem. Either the unit or the connector. Make sure all wires are seated and secure in the connector. I had two wires loose in the connector as the catch that holds the wire in place broke away due to age and heat.

If you AC is working correctly, you can test the fan and relay function by turning on the AC. The fan should come on immediately. If it does, the fan motor, relay , connector, and wiring should be OK and that leaves the sensor as suspect.

[alanmassengale]

This is a connector other than the 2 code reader connectors.
I replaced the under dash relay early on, no help. The connector looks ok to me, but I could be wrong.
My AC hasn't worked in many years, but when I turn it on the fan doesn't work. I know the fan motor works when I jump it.
Can I test if it was the sensor by jumping its connector? Or jump the control relay connector?

[MikeFleming]

Can I test if it was the sensor by jumping its connector? Or jump the control relay connector?
Yes. For the single-wire temp switch, ground it [to the intake manifold with key on, engine off. For the later 2-wire switch jumper between the two pins with key on, engine off.

You can manually push the relay arms to contact the pins inside the fan relay controller box. Pop off the cover.

[alanmassengale]

I jumped the 2 connectors on the switch connector with key on, no dice. Not expecting new switch to help, comes in Monday.
I'm guessing it is the old TRW relay or the wires on its connector. Or the fuseable link next to the voltage regulator.
Will probably be shopping for simple aftermarket controller soon. Heh.

No one knows what that extra open connector by the battery is?

[KevinK]

I found on mine, the relay arm was bent so it would not hit the contact when engaged. I only have 24k miles on mine so they are not very durable.

[Meotchh]

Thanks for the advice, I will definitely look into those resources.
The reason I suspect the ECM more than that though is that electronics guys say the capacitors (like the ones that went out in my radio to kill the AM) are only designed to live about 25 years, and this is 2021 now.


Electrolytic capacitors can begin to fail over time. This is easy to spot as they will begin to leak or split open. I haven't opened an ECM to see what type of caps are used in them, but I doubt they used electrolytic caps.

[Meotchh]

Look into the pins for the connector for the fan controller relay. When the relay module does not appear to be working, I start by reviewing the module itself & then work my way back. If the relays are not open & the board does not appear to be burnt, the module is unlikely to be the problem. The next item in the patch is the plug & the pins. Those can become bent causing them to lose contact with the circuit board contacts. It isn't easy to see this if you have the module in its housing & plugged in. It is really easy to diagnose issues at the connector or the relay module. If you remove the cover to the module, you can install the module in its bare form. It is easy to test for your resistance (to ground), check your voltage, & check your signals. If you are missing any voltage, signals, or ground at the board, check at the wires on the back of the plug. If you have the missing voltage, signal, or ground at the back of the plug, where the wires are crimped to the pins, then you have found the source of the problem. If you are still missing any of the voltage, signals, or grounds, then continue working your way through the circuit. From the plug, you can easily perform continuity tests between the plug & the other end of the branches of the circuit.

You can easily test fusible links by probing the wire with a test light to see if you have voltage on either side of the link. You can also perform a continuity test with a DMM.

[MikeFleming]

The yellow wire-fusable link feeds power to the EEC Power relay, the EEC and the fuel pump relay - all part of the EEC harness - It does NOT send power to the cooling fan. If the engine starts, the yellow fuse link is working.