[BRADBURYGROUP]

Hi Folks I have an Astra H 2008 1.8 XER that wont start or crank..

Lots of codes, engine ecu checked be ecu doctor and confirmed ok

Steering U2105 Communication with Engine control unit.
Brakes control Unit U2105 Communication with Engine control unit.
Steering column switch Module U2105 Communication with Engine control unit.
Column switch module U2139 Communication faulty.
Combi Instrument panel P0115 Coolant temp sensor - malfunction
P0500 Driving speed signal - malfunction
P0654 CAN message, engine speed signal - Signal not in range
P0550 Mileage signal - Value/ signal outside range
U2139 Communication with steering columns switch module - communication faulty.

The main ignition circuits relay is being activated, but the earth side switching the control unit relay is not, and the fuel pump relay is not getting switch power. continuity between relays and ecu on the relays.

Tried another used CIM but cant seem to code it although it is recognised

Has anyone came across this before?

Op com confirms no comms only with engine ecu, good can signals at engine ecu.

Any help appreciated.

 

[Fred Bassett]

So no authorisation is being given by the UHEC , IPC , CIM & REC to start ?

 

[BRADBURYGROUP]

So no authorisation is being given by the UHEC , IPC , CIM & REC to start ?

No Authorisation is what it seems like, but im not sure of the start logic sequence is in this and the wiring diagrams are a bit vague UHEC was coded by dealer (I have the security code) . not sure what IPC and REC are , dont you just hate acronyms ! lol

 

[Fred Bassett]

Simplest form of explanation . The Astra H uses a Can Bus system which as no host computer , the modules communicate with each other . The UHEC ( under hood electrical centre (fuse box) ) & the CIM ( column intergrated module ) & the IPC ( instrument panel control ) & the REC ( rear electrical centre ) all communicate with each other. Now what happens when you go to start your car is that these 4 modules check each other out , now if say the CIM is not communicating with the other 3 modules authorisation to start the engine will be refused . Andyl / Fire / Marks152 or nikh667 are experts on fault finding on the Can Bus system .

 

[BRADBURYGROUP]

Simplest form of explanation . The Astra H uses a Can Bus system which as no host computer , the modules communicate with each other . The UHEC ( under hood electrical centre (fuse box) ) & the CIM ( column intergrated module ) & the IPC ( instrument panel control ) & the REC ( rear electrical centre ) all communicate with each other. Now what happens when you go to start your car is that these 4 modules check each other out , now if say the CIM is not communicating with the other 3 modules authorisation to start the engine will be refused . Andyl / Fire / Marks152 or nikh667 are experts on fault finding on the Can Bus system .

Thanks Fred thats good to know , ill be having a go at it again today and see what transpires. I assume then its all Can Bus linked between the modules.

 

[Nick H]

Is the SVS (car with the spanner) light flashing at all with the ignition on? This normally indicates a problem with the 'immobiliser', which, as Fred says is a 'virtual' system comprising of UEC, REC, IPC, CIM, and ECM - which check each other for the correct data before allowing the engine to start.

The switch power for the fuel pump relay and the energised earth supply for the ECM relay both come from the ECM itself, along separate wires, essentially the ECM supplies an earth to switch itself on.

Seems all those fault codes relate to the engine ECM not being powered up. Check feeds into the unit first - fuses FE30 (10A), FE22 (7.5A) and FE21 (20A) - these are the direct 12v+ feeds into the ECM, ideally be worth checking them at the ECM with it connected/plugged in/ignition on, as you're checking the circuits under load. Check the ECM earth point also (bolts to the cylinder head on the right hand side around the connectors for the coilpack & cam position sensors).

CAN-bus can also be initially checked at least for it's connectivity - take the grey plastic cover off the actual diagnostic plug so you can get to the pins a little better - with the ignition OFF measure resistance across pins 6&14 (see diagram below for pins) - this tests the termination resistance across the entire high speed CAN, there's a 120ohm resistor in the ECM, and one in the ABS unit, so if all the CAN bus wires are in good condition and it's physically connected correctly, you'll have a resistance measurement of around 60 ohms.

Nick.

 

[Nick H]

Oh, and also check underneath the UEC for signs of water ingress or corrosion to the connector pins, this can affect lots as all those fuses come from this unit.

Nick.

 

[BRADBURYGROUP]

*****FIXED****** Ok Guys I solved it this afternoon. We had already replaced the UHEC as it had corrosion on the terminals to the CAN BUS side, but the problem wasnt that but probably would be soon enough.... You are right with the wiring checks and the earths switching the relays, the problem was with the main power supply to pin 32 - battery supply Nick was spot on though. It was reading 12v on DVM but when plugged into the ECU we had voltage drop down to just 1v using a back pin and a fuse temp link, I ran a temp fused supply to pin 32 and all restored. so we have a a resistance somewhere in that cable between the ecu and fuse box which will be rectified tomorrow morning. Thanks for your input help and support very much appreciated.

 

[Nick H]

Fab that's good news, a good find - nice one

Nick.

 

[BRADBURYGROUP]

Fab that's good news, a good find - nice one

Nick.

For your info found the corroded wire in the loom under the thermostat housing.