EKP Module pin #2 wire getting very hot

[synergy141]

Hi guys. I'm having a wiring issue with the pin #2 wire that goes to the EKP module for the fuel pump. The one wire (pin 2 wire) gets very hot almost instantly once the car fires up. It's hot enough where you can't touch it.

No fuses are getting blown. The car drives fine still.

What would be causing this? Is my fuel pump drawing too much power? Or maybe some wiring insulation down the line is broken and shorting out?

[Panici]

Hi guys. I'm having a wiring issue with the pin #2 wire that goes to the EKP module for the fuel pump. The one wire (pin 2 wire) gets very hot almost instantly once the car fires up. It's hot enough where you can't touch it.

No fuses are getting blown. The car drives fine still.

What would be causing this? Is my fuel pump drawing too much power? Or maybe some wiring insulation down the line is broken and shorting out?

Simply put, a hot wire means you either have too much current (amperage) or too much resistance (corrosion, poor connection, etc).

You could have a partial short to ground (that is unfused), or your fuel pump could be pulling too much current if it's oversized.

Your wiring or connections may be corroded somewhere.


Either way, wiring getting that hot is a safety concern. If your wiring insulation gets hot enough somewhere, it will catch fire. It's usually these kinds of electrical fires that burn cars to the ground.


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I would start at the area you have found to be heating up, and check as much of the wiring as you can.

You can also measure current draw with a multimeter at the supply side and at the load side. If you have a mismatch, you have a short to ground somewhere between.

Without being familiar with the M54/S54 electronics, i'm assuming the wire in question connects the fuel pump to the EKP module?

[synergy141]

Thanks for the response. It must be shorting out somewhere as fuse 11 is getting grounded. I can tell via my multi meter

[Panici]

Thanks for the response. It must be shorting out somewhere as fuse 11 is getting grounded. I can tell via my multi meter

Are you getting that conclusion from testing for continuity?
The meter may be showing a ground through the fuel pump windings.

[synergy141]

Yes continuity. Maybe I should disconnect the fuel pump wiring at the pump

[Panici]

Yes continuity

It's normal to see continuity to ground through the fuel pump windings with the circuit de-energized. You obviously can't test the continuity with the circuit powered, since it uses the multimeter's onboard battery.


I would unplug the wire at the fuel pump, and then check continuity to ground. This would show any shorts, but only to ground.


You could also unplug the wire at the fuel pump, and put the multimeter in-line between pin 2 and the wire. Set it on amperage/current measurement, and power up the system.

If you get anything other then zero, you have a draw somewhere along the wire.
(ie, you have damaged wiring insulation on two wires, and another circuit is drawing power on pin 2)

Be careful though, you may damage your multimeter if it has a small max current measurement rating. In that case you will need a better meter, or a properly sized shunt resistance to measure voltage across.

[synergy141]

The wire only gets hot the first few inches from the EKP module. It's normal everywhere else

[Panici]

The wire only gets hot the first few inches from the EKP module. It's normal everywhere else

You're able to check the entire length of the wire?

It may be that the EKP module is the limit of the system. That is to say, it will fail before the wire fails (catches fire, etc)

Unfortunately if that is the case, it still doesn't rule out a short somewhere else along the wire.


It's also possible that there is something internally wrong with the EKP module. Bad solder joint or connection could cause a high resistance, creating heat.

[synergy141]

You're able to check the entire length of the wire?

It may be that the EKP module is the limit of the system. That is to say, it will fail before the wire fails (catches fire, etc)

Unfortunately if that is the case, it still doesn't rule out a short somewhere else along the wire.


It's also possible that there is something internally wrong with the EKP module. Bad solder joint or connection could cause a high resistance, creating heat.

I've swapped EKP modules with the one out of my e46 m3 and still have the same issue.

I followed that wire from the EKP module in the glove box, through the fire wall right to the fuse box and there is no heat in the wire at those parts. I felt the wires right to the fuel pump and they felt cool while running, So the heat is only occuring a few inches up from that module.

[Panici]

I've swapped EKP modules with the one out of my e46 m3 and still have the same issue.

So that rules out a bad EKP module.


Here are some next steps:

I would unplug the wire at the fuel pump, and then check continuity to ground (at the EKP module). This would show any shorts, but only to ground.


You could also unplug the wire at the fuel pump, and put the multimeter in-line between pin 2 and the wire. Set it on amperage/current measurement, and power up the system.

If you get anything other then zero, you have a draw somewhere along the wire.
(ie, you have damaged wiring insulation on two wires, and another circuit is drawing power on pin 2)

Be careful though, you may damage your multimeter if it has a small max current measurement rating. In that case you will need a better meter, or a properly sized shunt resistance to measure voltage across.

Additionally, you can put the multimeter in-line between pin 2 and the wire. Set it on amperage/current measurement, and power up the system with the fuel pump connected. This will show the total current draw including the fuel pump.
As above, make sure you aren't pulling too much current through your meter when doing this.

[M3PO]

In the S54 wiring guide, EKP Pin #2 is:

*edited out*

Are you sure that this is wired correctly? Its not clear to me how it should be wired...

[Panici]

In the S54 wiring guide, EKP Pin #2 is:

power for oil level sensor [connect to switched 12v,hot in ACC and runing]

Are you sure that this is wired correctly? Its not clear to me how it should be wired...

You sure about that?

http://www.r3vlimited.com/board/showthread.php?t=275042

EKP-modul [regulated fuel pump relay must be used, the E30 relay will not work properly,]
EKP pin 1 [pulsating signal from mss54 connector X60002 pin 11 then to X6021 pin 1 black/violet (black 4 pin connector), I just wired this directly]
EKP pin 2 [to fuel pump,to whatever pin is on your E30 for fuel pump]
EKP pin 6 [battery +12]
EKP pin 7 [ground]
EKP pin 8 [switched +12, DME relay X6021 pin 2, white/red wire]


Black 8 pin connector:
Pin 1: starter cranking, fat black wire [connect to starter turn on wire, ignition switch]
Pin 2: power for oil level sensor [connect to switched 12v,hot in ACC and runing]
Pin 3, 4 ,5, 6 [are all empty no wires]
Pin 7: gray wire [clutch switch module on non SMG harness, can’t use it on e30]
Pin 8: yellow/black wire goes to X60003 pin 19 [to tire pressure module, no use on E30]

[M3PO]

You sure about that?


http://www.r3vlimited.com/board/showthread.php?t=275042

My bad lol! Looking at the wrong connector!

[squidmaster]

Does the module get hot at all itself? Try splitting the ground wire and ground it securely close by.

[synergy141]

I'm going to take some time tomorrow and go through everything again.

I've still been driving the car but paying close attention the wire temp. It will randomly get hot now and other times its just a tad warm. It must be worn somewhere and grounding.

Does the module get hot at all itself? Try splitting the ground wire and ground it securely close by.

Module does not get hot, just the wire