Italamec Key Light Delay Module

I had a look at the internals of my (working) Italamec "relay" and put the info on how it works on one page, to assist anybody who may have problem with it.

The Italamec module (no relay inside) has two functions:

1. Connects left and right door switches with a large diode to enable the roof light to come on with either door switch. On my 1991 RHD Euro 348, the roof light is hard wired to the left door so, if Italamec is taken out, the right (driver's) door does not activate it.

2. Provides +12V to the key light continuously while the driver's door is open and for ~15 sec. after the door is closed. The trigger for the delay circuit inside Italamec is taken from the cathode of the large diode (the diode cathode, "I" pin of Italamec, is connected to the driver's door switch - LHD left, RHD right). In this way (due to the diode), the key light is operated by the driver's door only.

If the Italamec is bad (the roof light does not work with one of the doors), the module can be taken out and the pins "P" and "I" in its socket can be bridged to get the roof light function by both doors.

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Small correction: on LHD cars, the roof light is hard wired to the right door switch.

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The key bulb is grounded on one side and gets +12V from the Italamec's "L" pin. To test the bulb and its wiring, pull the Italamec out and bridge the female pins "30" and "L" in its socket (verify that you have permanent +12V in the "30" socket). The light is hard to see in daylight, it is only visible when looking directly into the key slot. If the light works with the bypass, then your Italamec is bad but it can be repaired - see the transistor types I wrote on the page, both are available on Ebay. There is also a 220 uF capacitor which can be a suspect.

 

I can't help with the way of changing the bulb but, if your bulb has burnt and you can't get the original, you can replace it with small 12V bulb, usually available in radio shops. If using a universal bulb, it shouldn't be more than about 0.5-0.6 Watt (~50 mA) as the transistor driving it (the MPSW05) has only 1 Watt dissipation and it has no heat sink.

 

You are welcome to add the info. One suggestion: replace your note "Diode orientation depends on LHD/RHD" with "Pin I goes to the driver's door switch, pin P to passenger's" or "Pin I goes to the left door switch on LHD, right door switch on RHD" or similar.

The large diode is inside the Italamec (across pins P & I) and its orientation is not changed for LHD/RHD but the wiring to the pins P and I is different for LHD and RHD; pin I is always connected to the driver's door switch, wherever the driver's side is, and pin P goes to the passenger (easy to remember).

 

Hi Ian. As I was going to check the voltages on my TPS-s, I looked at your 348 Motronic 2.7 Wiring Diagram as well as at the original one. I noticed a discrepancy in the connections of the left and right TPS-s to their respective ECU-s and could see that on your diagram (which follows the original one), you have put question marks at the Right TPS. It appears that, in the original diagram, the connections of the IAC and TPS to the ECU have been swapped-over by mistake. I believe that the IAC and TPS connections to the ECU shown for the Left bank are correct and that the diagram for the Right bank should be corrected, i.e. should be same as shown for the Left bank. This is because the instructions in the manual for checking the voltages on the TPS state that, for both banks, the voltmeter should be connected between ECU pins 19 & 53 to verify that there is 5V supply. On the diagram for the Left bank, ECU 19 (ground actually) goes to Pin 1 of the TPS and ECU 53 goes to Pin 3 of the TPS and I have just verified that I have 5V between Pins 1 & 3 on both of my TPS-s.

I have not physically verified that the Right TPS is connected to its ECU in the same way as the Left one but it looks obvious to me that the connections TPS & IAC to the ECU on the Right bank are wrong.

The mentioned instructions for the TPS voltage checks are also confusing. They only mention connection of the voltmeter between Pins 1 & 3 of the TPS (Pins 19 & 53 of the ECU) to verify the 5V and then state that 400-600 mV is correct voltage on the TPS (at idle position) but do not state that this should be measured between Pins 1 & 2 of the TPS (Pins 19 and 12 of the ECU).

 

You need to make the following further changes to the RH bank connections:

IAC 1 - OK
IAC 2 - move from splices "VVV..." to splices "NNN..." (ground)
IAC 3 - OK

TPS 1 - move from ECU 12 to ECU 53
TPS 2 - move from splices "NNN..." to ECU 12
TPS 3 - move from ECU 53 to splices "NNN..." (ground)

RH TPS Pins 1 & 3 have to be connected opposite to how the LH TPS pins are connected since they are rotated in opposite directions (LH anticlockwise, RH clockwise).

 

Sorry, my previous info was wrong. I was confused because, as I just found out, the TPS pin markings on the diagram 1,2,3 do not exactly correspond to the 1,2,3 markings on the TPS itself. The diagram Pin 2 (wiper of the TPS) is Pin 3 on the TPS itself (and vice versa).

After checking directly on my 348, I can confirm that your "F348_27_Correction" is all correct (discard your "F348_27_Correction2").

As you will note (looking at the diagram pin numbering), on the Left TPS, Pin 1 is ground and Pin 3 gets +5v from the ECU Pin 12; on the Right TPS, they are reversed - Pin 1 gets +5v from the ECU Pin 12 and Pin 3 is ground. This reversal of 5V supply polarity to the end terminals of the TPS potentiometer is necessary because the Left TPS is rotated counterclockwise and the Right one clockwise.

You can also change your wording (at the Right Bank green splices) "12V power splices" to "ECU provided 12V power splices" and put the same description at the Left Bank brown splices.

 

I don't see that any relay provides power to the "12 volt splices". The "12 volt splices" get power from the ECU and the splices provide power to one side of the coils of the Fuel Pump and Injection relays. The other side of these relays is grounded by the ECU to switch them on as required.

The TPS connections:

I (again) overlooked one detail - on your "F348_27_Correction" diagram, the existing Right TPS pin numbering happens to be as per the numbering on the TPS as far as the links to the ground and the ECU are concerned so you should leave them as they are. Just move the potentiometer symbol up a bit (until aligned with line 2), link 1 to its other end and link 3 to the middle of the pot symbol. Something like this:
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On the diagram for the Left TPS, move the pot icon down a bit (until aligned with line 2), link 1 to its other end and link 3 to the middle of the pot symbol (mirror image of the above pic).

I hope this finally clears the Ferrari mess.

 

Absolutely right. I did earlier follow the 2.5V line (a number of times) from the 12V splices to the relay L and saw it connected to the relay pin 87 but, due to some brain lock (or age catching up), I took it to mean one of the relay coil pins, even though I have known the meaning of the relay numbers for at least 40 years (and I didn't look just a bit up to see that 87 goes to the relay contact). Relay L (Injection) is activated at ignition "on" and it provides power to one side of the coil of relay N (fuel pump) and gets it ready to be switched on by the ECU during cranking and during engine running.

I will have a look at your final diagram tomorrow and let you know. Cheers.

 

Your diagram Motronic 2.7 Ver. 14, everything good - just a couple of small changes:

1. The "+5V" should be at Pin 2 on the Left TPS and at Pin 1 at Right TPS.
2. At the splices, replace "ECU provided" with "IGN".

 

Put "+5V" also at pin 1 of the Right TPS.

As to the power to the "splices", it is controlled by both, the Ign. switch and the ECU. The ECU will normally allow the relay L (injection) to be switched on at every ignition on but it will switch this relay off in the case of bank shut-down. Perhaps you can put "IGN/ECU controlled 12V pwr splices".