Technical Electrical issue

[DLS84]

Hi all. Over last few weeks bin having a electrical issue where doblo 1.9jtd ether cuts out while driving n temp gauge goes funny n dash lights come on. Now it would just continue but got worse and worse to point no start. AA can't tell me issue ether. I've got immobilizer light on and battery, AA could not communicate with ecu even checked for power which they confirmed it had.

 

[varesecrazy]

Have you ruled out the Main Battery to Motor + Body cable?

They can rot internally.. making and breaking as you drive

@Dragon Man will have seen a fair bit of this I suspect...

 

[DLS84]

Have you ruled out the Main Battery to Motor + Body cable?

They can rot internally.. making and breaking as you drive

@Dragon Man will have seen a fair bit of this I suspect..

 

[DLS84]

I've tried a jumper cable to various points no difference AA spent an hour, no joy

 

[varesecrazy]

That reads like AA made a direct power circuit to ECU.. but ECU still wouldnt appear to function


Usual questions:

Have you had it long..?

No work done in last 3 months..??


No flat battery issues..etc ?

 

[Dragon Man]

2002 onward fiats have an annoying thing that they do. they block their own keys from the immobiliser say if the battery is getting tired. you pretty much cant do anything about it other than reset the ECU with a pc and the right software and re-lean the rfid's in the keys. a Fiat dealer should be able to do it but the original starting / cutting out issue needs to be looked into. i'd check the ECUs earthing.. see how that is. the fact it cant communicate with it says that it can only be a power issue or wires have been cut/corroded through. check the ecu plug for corrosion, never seem to get it in earth pins only live pins.
do you see have the ability to crank? if so try manually powering your fuel pump relay. i had it once with a doblo where it would only run if you did that.

 

[DLS84]

That reads like AA made a direct power circuit to ECU.. but ECU still wouldnt appear to function


Usual questions:

Have you had it long..?

No work done in last 3 months..??


No flat battery issues..etc ?

Had jus ov a year. No flat battery. Las 3 months roughly timing done, crank sensor temp sensor. Battery has bin changed to new.

 

[DLS84]

2002 onward fiats have an annoying thing that they do. they block their own keys from the immobiliser say if the battery is getting tired. you pretty much cant do anything about it other than reset the ECU with a pc and the right software and re-lean the rfid's in the keys. a Fiat dealer should be able to do it but the original starting / cutting out issue needs to be looked into. i'd check the ECUs earthing.. see how that is. the fact it cant communicate with it says that it can only be a power issue or wires have been cut/corroded through. check the ecu plug for corrosion, never seem to get it in earth pins only live pins.
do you see have the ability to crank? if so try manually powering your fuel pump relay. i had it once with a doblo where it would only run if you did that.

I noticed an old thread where you had done that. Yes I can crank it jus won't fire. Not sure how I do a bypass was trying to work out from your old thread.

 

[Dragon Man]

in the image below, the blue wire is an ignition live, the black wire is just an earth. the other 2 wires are just there to lift the relay from the original sitting position so i can manually control the relay with an ignition live.

just to note, any engine management light on any vehicle older than 2008 will not be a fail on an MOT

 

[DLS84]

in the image below, the blue wire is an ignition live, the black wire is just an earth. the other 2 wires are just there to lift the relay from the original sitting position so i can manually control the relay with an ignition live.

just to note, any engine management light on any vehicle older than 2008 will not be a fail on an MOT

So connect the 2 7.5amp fuses. Then on relay 2 wires in slots and then 1 pin earth leaving 1 pin empty

 

[Dragon Man]

on the 2 small pins on the relay connect one to ground or battery negative, the connect the other small pin to fuse F16 by pulling the fuse out and trapping the wire in it as you put the fuse back in. this will give an ignition live.

the big pins on the relay just make them connect using some wires to the original pin slots on the relay socket.

 

[jackwhoo]

If one of the sensors that requires 5v from ecu goes short circuit I believe it can cause the 5v to read 0v.

The above can be checked by unplugging each sensor in turn and checking to see if 5v reference has returned......probably good to cycle the ecu on and off between each test in case ecu turns off 5v if short detected.

 

[jackwhoo]

Can you describe "temp gauge goes funny" a little more?

 

[DLS84]

Can you describe "temp gauge goes funny" a little more?

It's only warning I got, temp gauge would suddenly jus go up on red light come but go bk down. Only way I could dicribe it like ignition turn on it does it then.

 

[Dragon Man]

like it does a self test. hmm it could have been some kind of power loss to cause that. sounds daft but try removing and resetting all fuses it could be a bad connection on one.

 

[DLS84]

I had cheap obd reader in till it packed in to try n locate issue. Only thing I thought strange obd voltage would drop during it's hissy fit. Fuses have checked but I try it. Bin stuck 3 week now.

 

[jackwhoo]

The battery negative cable is a week point after a number of years use.

The cable can break down internally under the insulation .

If it is the sort that goes from battery to body connection then to gearbox /engine , the crimp connection at body can work loose. Plus corrosion between body and bolt on connection.

Both battery terminals can suffer too.

 

[DLS84]

The battery negative cable is a week point after a number of years use.

The cable can break down internally under the insulation .

If it is the sort that goes from battery to body connection then to gearbox /engine , the crimp connection at body can work loose. Plus corrosion between body and bolt on connection.

Both battery terminals can suffer too.

Tried jump lead to various locations and has new battery

 

[jackwhoo]

Tried jump lead to various locations and has new battery

Yes saw that you had tried jump lead and has new battery .
Battery connectors?
Don't know where you put jump lead?

Use two jump leads one battery negative connector to clean metal on engine or gear box , the other from clean metal of engine or gear box to clean metal on vehicle body(this is more import than first jump lead if engine cranks on starter motor without first jump lead)

 

[DLS84]

Yes saw that you had tried jump lead and has new battery .
Battery connectors?
Don't know where you put jump lead?

Use two jump leads one battery negative connector to clean metal on engine or gear box , the other from clean metal of engine or gear box to clean metal on vehicle body(this is more import than first jump lead if engine cranks on starter motor without first jump lead)

Can't say I remember using 2. My knowledge is limited but 3 or 4 points on engine inc near belts and say for body. It will crank but only 2 lights. No eml or glow plug lights. Battery terminals are original but AA checked battery 1st.