ECU Fault Code 74: Analog 5V Supply Error

[ayjayef]

I'm wiring up a Fury and all was going well (see: before.jpg) and next morning, without any changes and nothing touched I turned the ECU back on and it looked like this (see: after.jpg).

Faults are:

[10:33:03 AM] ECU Fault Code 74: Analog 5V Supply Error
[10:33:01 AM] ECU Fault Code 73: Aux 9/10 Supply Error
[10:32:59 AM] ECU Fault Code 47: An Temp 2 below Error Low value
[10:32:57 AM] ECU Fault Code 44: An Temp 1 below Error Low value
[10:32:54 AM] ECU Fault Code 35: An Volt 9 below Error Low value
[10:32:54 AM] ECU Fault Code 32: An Volt 8 below Error Low value
[10:32:52 AM] ECU Fault Code 11: An Volt 1 below Error Low value

So it seems that Fault 74 is causing all the sensors to error which makes sense.  It also seems that Fault 74 is because 5V is shorted to ground.

I removed the sensors one by one (no difference) and checked the wiring (no problems found).

Then I removed the Link A&B connectors from the ECU to see if there was anything connected to ground (Link A 25,34 and Link B 25,34 are the only pins earthed and they were meant to be)

So I can't find any problems in the wiring and am starting to wonder if the ECU has a problem with the 5V.

What is the minimum wiring needed to run the ECU to test the ECU 5V channel?

Link A5 (14V+)

Link A25,34 (Ground)

...and then test the 5V+ on Link A32?

 

 

 

[Adamw]

Just pull the 5V wire out of the ECU connector (leaving all other wires connected) and see if the 5V out parameter returns to normal, if it does that suggests there is a short somewhere.  The pins can be extracted quite easily:  https://drive.google.com/open?id=1MnJlNTBhX_ccv40PbVgIi9XTy4HbXEfJ

[ayjayef]

Thanks Adam,

I'll test that tonight when I get back.

yeah, the superseal connectors are good for removing a pin, that's about the only thing I didn't think of in my frustration.

 

So for future reference (and I'll make a test loom)  what was the minimum wiring needed to fire-up the Fury?

 

[Adamw]

2 minutes ago, ayjayef said:

So for future reference (and I'll make a test loom)  what was the minimum wiring needed to fire-up the Fury?

Just the +14V (pin A5), and one of the main grounds (A34 or A25)

[ayjayef]

3 hours ago, Adamw said:

Just pull the 5V wire out of the ECU connector

Good news - that was a simple test that worked.  ECU now shows "5V Out (V) 5.00" and I can also measure 5V+ at that pin (A32).

Now to go through the wiring again to see what I missed last time.

 

[ayjayef]

Bingo.  

As you all know, intermittent faults can be a nightmare.  Happily found this one though so am posing the punchline in case someone else finds this thread with a search.

Carefully soldering and heat-shrinking all the 86 pins on the 3 factory connectors I managed to dribble a solder spatter into the middle of the plug (doh!)

It was small enough not to notice, big enough to cause a 70 ohm "short" intermittently so it got past my previous conductivity testing.  I'm just glad I hadn't filled it with epoxy yet!

 

Thanks heaps Adam for the help in isolating my oops from the ECU.

Andy.