2 litre DOHC Ford Engine

[ggrum]

One for the electrical bods. My Cabrio has the 2 litre 8V DOHC engine. Is it true to say that when the ignition is off there is no power at all to the ECU? Or is there a feed somewhere to keep it 'alive' all the time, for example to hold up a memory chip. The reason for checking is that I would like to fit a battery isolation switch for when the car is not in use for long periods.

[cameronfurnival]

Re: 2 litre DOHC Ford Engine

yes there is a keep alive supply for the ecu which if memory serves is actually pin 1.

[chris_cussen]

Re: 2 litre DOHC Ford Engine

Depends, if you have the carburettor version of the engine then its OK to disconnect the power, mine was off for 7 years as I built my cabrio and was only powered up with the ignition on. The EFI version has a EEC-IV ecu, but I know nothing about it.

[cameronfurnival]

Re: 2 litre DOHC Ford Engine

If you remove the keep alive feed it just means that when it gets connected up it will boot from scratch - no big deal but any stored data in it will be lost.

[philcoyle]

Re: 2 litre DOHC Ford Engine

Hi Grum,

It will make no difference at all to the ECU, and fitting an isolator switch is a step in the right direction.
The EEC IV ECU only stores faults it finds, upon start up, it sends out a voltage to the various sensors and switches and diagnoses the signal return before it makes up its mind if it is going to start or not ( I apologise for my sense of humour) If you disconnect it for ten years it will still only give you the faults it finds on start up, otherwise every time you disconnected the battery you would have to get it remapped.

I have had an isolator fitted for the last twelve years and I run with the EECIV ECU without any problems, if you have any faults when you disconnect the power supply they will be there when the ECU runs through its start up programme no matter how long it has been or if it had power connected or not.

Try not to confuse our ECUs with the modern day ones as they are programmed differently, chips in the ignition key, transducers on the ignition barrel, alarms and suchlike.

[ggrum]

Re: 2 litre DOHC Ford Engine

Many thanks, chaps. Looks like I can go ahead with a battery isolator switch.

[philcoyle]

Re: 2 litre DOHC Ford Engine

You may want to connect a cigarette lighter socket wired directly to the battery if you wish to trickle charge through the winter. Are we allowed to say cigarette socket these days or is it a 12v power outlet thingy.

[Dane_Rescueman]

Re: 2 litre DOHC Ford Engine

Your EEC IV does have a KAP installed. The KAP was introduced half way through the EFi Pinto Sierra manufacture. The EEC IV, complete with a new programme was fitted to the DOHC engine which did have KAP. If you keep the pin 1 powered as I do via a separate 1 amp fused connection to the battery this will be fine. It actually only takes milliamps so will not flatten the battery. If the KAP becomes disconnected then there is no problem, the system will start from the factory programme. The engine will run OK. It will relearn the optimum settings for your engine. On my version of the EEC IV, following a disconnection the engine should be allowed to idle for 2½ minutes and then run at 2500 rpm for at least 30 seconds and this will allow the system to relearn the requirments of your engine. In practice, driving about five miles does much the same thing! The very early EEC IVs (roughly pre 1989) did not have KAP and just ran on the pre-programming installed at manufacture. Most of the EEC IVs were OBD 1 which was a very simple two digit system self check. A simple reader, or just a light bulb, can be used to read these once you have the readout codes to hand.

Some battery isolator switches have a fused by-pass exactly for the KAP reason. They are easily available from most after market suppliers.

(KAP = Keep Alive Power)

[ggrum]

Re: 2 litre DOHC Ford Engine

I do use a trickle charger through the 12v power socket but if I forget to use it for more than a few days it gets pretty warm bringing the battery back up to full charge which is why I thought of using the isolator switch. Apart from the ECU KAP the battery also feeds a clock and an alarm system which has a permanently illuminated LED (not flashing as normal). The battery is virtually brand new so I guess the combined current draw of all three is significant. I don't need the clock (can't see it from the drivers seat anyway) so may remove it.
Thanks again for all your input.

[cameronfurnival]

Re: 2 litre DOHC Ford Engine

Interesting - and I have learned a lot here - Dane, can you tell me how to read error codes with a bulb?

[Dane_Rescueman]

Re: 2 litre DOHC Ford Engine

Hi Cameron. A bulb will work but I think it is far safer, for current draw reasons, to use a 12v LED or an analogue multimeter.
Make sure the engine is warmed up.
Connect the LED or multimeter as follows.
One lead to the battery+, the other to terminal 3 or output pin of the Ford SD connector either 3 pin or 5 pin.
use a jumper lead to bridge the remaining two terminals (1&2) in the SD connector.
Start the engine and allow it to idle.
after 45 seconds the LED will begin to flash the two digit fault codes:
The two digits appear as two series of flashes. The first series are the tens and the second series the units. These are each preceeded by one second flashes. the pauses are about 1 second too.
The tens are separated from the units by a pause of approx 4 seconds.
The various codes are separated by a 6 second pause.
The number of flashes needs to be counted and written down to show a two digit number.
continue retrieving the codes until it shows no more.

If code 11 is noted then no faults exist or have been stored.
On EEC IV without KAP the faults will not be stored and will only be seen with the ignition on.

With the later EEC IV it gets complicated and although you can get the fault codes the similar way it would be better to beg borrow or steal a fault code reader., anyway:
switch on the ignition - no need to start up yet.
after 45 seconds the LED starts to flash.
Readings are as before, however, the pulses are now 0.5 seconds on and 0.5 seconds off.
the code digits are spaced by 2 seconds.
A 4 second pause is between codes.
after all codes have been transmitted there is a pause of about 7 seconds.
there could be another pause of 7 seconds followed by a single flash.
after this, soft codes from the KAM (Keep alive memory) will be transmitted.
There are command codes that need to be acted upon otherwise we can cause a fault code to be stored in KAM. This will then need to be read by starting over. This is why the later EEC IVs would benefit from a code reader as it is so easy to lose count!
Code 11 shows that there are no faults recorded.
Code 10 shows that the system is about to enter a "wiggle" test.
At this stage manipulate any wiring, plugs etc (no, don't disconnect them, just wiggle).
Any faults will appear as previously, with a number.
The wiggle test codes will only be available with ignition on on the non KAP EEC IVs but should be recorderd on the KAP capable types.
Now start the engine, then wait 4 seconds and use the jumper lead to bridge the 1 & 2 terminals in SD socket. The meter being already attached.
Now collect the codes in a similar way to previously.
I prefer to use an analogue meter as you will see a jolly good flick of the needle when the codes are produced. A digital meter may well not respond quickly enough.
The EEC IV with three digit fault codes and the later EEC V and Weber IAW can be read in the same way but the chance of missing a code, flash or space is very likely which could end up in recording gobbledygook! Here a code reader becomes more essential.
The basic codes for the earliest EEC IV is very simple.

11 no faults
12 AFS fault
13 Coolant temp sensor fault
14 Air temp sensor fault
15 TPS sensor fault
(22 Number two AFS in early injected V engines at fault)
23 Airflow sensor AFS number 1 or2
31 Wiring or module fault
32 Wiring or module fault.

I have the list for the later EEC IVs of which there are nearly 100 codes and vary between engine types. There are many more on the EEC IV enhanced 3 digit codes too.
The EEC V Is much better seen on the applicable code reader as the fault codes are not show; just the fault itself!
You can see that the basic EEC codes will not be difficult to do with a LED or meter but with the later ones, the chance of losing count is very strong! I have just tested my old EEC IV and got a number 11 so nothing to report!
Good luck with this!