Vauxhall/GM common ECU failures


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Astra H 2005-2011 Twin-Top  Suffer problems with roof wiring harness into the nearside corner boot mechanisim (to blue and green multiplug).  Hydraulic pumps are robust!  Roof can get stuck half way folded due to exceeding the "nine minute alarm".  There is a defined method to reset this, by accesing the two hydraulic roof motor relays and running the hydraulic pump via a slave power supply to re-pressure the system.

Vectra Omega A B (all models except C) suffer near impossible to find continuity faults in main wiring harness connected to the main ECU (Kelvar wrapped sheath).  Omega with BMW 2.5 diesel engine a gem! Only minor hot restart problem known, normally knock sensor on engine. Be aware of glowplugs in 2.2D engine (see note for Frontera below).

Vectra B 1.6/1.8 16V 96-98 suffer output signal problems from ECM PIN number 1 voltage should read 10.4V with ignition on but engine not running, any other value should be seen as suspect.

Vectra B 2.0 95-00    Simtec 56.5 modules suffer output problems to camshaft position sensor, readings should be 666hz, all-thou intermittent problems can only be found by scrutinising scope pattern using an oscilloscope. Output pin 13 (31)

2.5 V6 models a nightmare, CATS fail wholesale (cats need back pressure testing plus testing with four gas analyzer).  Engines are prone to cylinder head failure between bores (they do not pressurerise coolant as a rule, so leakdown test thru plug ports, only conclusive method of diagnosis).  Cambelt replacement vile job, most small independent garages just won't do it.  Avoid any form of major electronic diagnosis like the plague, motion sensor faultcodes common, even when sensors show perfect waveform on scope and are working perfectly with host wiring in excellent shape.  Piezo knock sensors on engine block suffer from bad earths and component failure (very difficult to get to and backprobe to prove function with scope). 

Corsa 2008 > Service Light 2  If you are unable to extinguish the Service Light 2, it is because you have bulb failure.  Service light 2 is a bulb out warning indicator and must be reset after changing a bulb.

Astra D F + Vectra  EDC diesels, all years, suffer from electronic failure (mostly hunting while idling).  Injection pumps cost a fortune to overhaul 500+ so on car testing (PGS5-16) & off car bench testing is very cost effective.  If only to eliminate suspect pump control module from replacement additional info on testing  Can-bus ribbon tape cables from early pump control unit to main ECU, amounts for 15% of all pump problems.

Astra 1.7 TD Isuzu engine  ECU a common failure. Symptoms are complete non start or a spurious fault code blaming the spill valve.  Alternator problems are caused by water leaks from coolant pipes. 

Later GM 1.7 TD engine suffer very difficult to diagnose intermittent faults with injection pumps, its not been unknown for one or two of out trade customers to enact a complete replacement of the pump and not to cure the problem, as the fault has been in the host wiring.  It pays to have the pump tested, if only to exclude it from the diagnostic procedure and thus proving function of the pump by the substitution of an expensive new one.

Astra G 1.7D DTi 20-06 suffer harness failure to Bosch ETC sensor-coolant temp.  Symptoms include erratic idle, stalling & poor starting from cold.  GM EDC diesel pumps are known to fail from "cavitation" due to an ingress of excess water.  Water separates out from the fuel over time in diesel filters, and if the filter housing if not drained down at intervals.  The water will damage the pump beyond repair.  Most car manufacturers are now fitting new type water level sensors to filter housings on new models.  Supermarket fuel is jokingly called emulsion in the trade, due to its high water content.  Its cheap for a reason!   Some early VP44 pumps are known to fail due machining errors in the axle rota head, a few of these wreck the alloy pump body, rendering the pump unserviceable.

1.9CDTi suffer from programming problems relating to the Bosch EDC15, the car will go into limp mode and record some very strange codes.  Air intake systems are over complicated, plus they eat turbos-intercoolers.  Whole 1.9CDTi engine is just a bad concept (Fiat design made in India) for what should be a good fast car.  Best avoided over 50.000 miles unless you have money to burn.  Auto gearbox models even worst news.  Only good news is, if it chucks the cambelt off, it may only break all the followers not bend the valves if you are lucky.

1.9CDTi suffer from DPF (diesel particulate filter) problems requiring regeneration or replacement.  It is now coming to light, there is a programming issue.  We can re-program your module with the update to change the passive regeneration parameters.

1.9CDTi  Do attempt to change glowplugs, unless you equipped with correct threaded extractor and centering tool to drill them out.  50% of the stupid undersize pencil glowplus snap off when being removed.  Also do not attempt to change the cambelt without the correct lower timing plate, it is just not possible without the corect tool.

1.9CDTi suffer from air manifold intake flap failures at 65.000 miles (ish).  The intake manifold blocks up with soot becuase the EGR valve is open too much, the solenoid which controls the flaps has so much power it breaks the top control bar.  Nasty expensive job to do!  Replace cambelt, waterpump, remove diesel pump and one stud that holds it to the head assembly to  gain access to the manifold bolts.  The solenoid is very-very to difficlut to get to.  We have done as many as three a week in our workshop, its an 8.5hr job!  Which is reason enough not to buy the Fiat DTH engine.  We have put three on the same taxi which has done 280k.  pictures of this job in process

GM diesel engines 2.0/2.2 DI-DTL-DTH.  Beware of the engines fitted with the VP44 PSG16 pump!  Pumps fail wholesale, costing owners a fortune.

Zafira 2001-05 1.6 1.8 simtec systems suffer MAF ecu input problems.  No faultcodes present.  Massive underfueling symptoms created by the ECU.

Mariva 2003+  Suffer steering column torque sensor failure, symtoms include EPC light illuminated and loss of power steering assitance at full lock - low speed.  Repair is expensive, and the column needs calibrating after fitting.  We have had to replace motors as well, these are silly expensive.

Corsa (late models) 2000+ Suffer airflow meter problems! & fragile coil in cap DIS system prone to mechanical damage.  Charging faults nearly always can be traced back to the plastic back of the alternator falling apart on late three cylinder models (good engine/fragile alternator).

Corsa B  97-00  suffer ECM output failure from Pin number 29 to throttle position sensor (a good output is 5V when testing).  Any other value should be seen as suspect.  All  models can suffer ECU output problems to crankshaft position sensors, voltages upto 14V should be expected.  Output to Idle control valve can have problems it should be 11V.

Tigra 1.4 95-00  Suffer poor earthing from ignition coil at the connection to throttle body.  GM sell a tin (gold) plated screw for the upgrade (no joke)

Frontera  Suffer leaking injector seals.  Fault very difficult to diagnose.  Injectors with solenoid on the top are very fragile (bottom and top seals fail causing bad starting).  Handle with care!  Plus be aware, pencil glowplugs fitted to 2.2D are prone to shearing off in the cylinder head (it pays to test the pencil gllowplugs first with an inductive amp meter and just change only the ones that fail testing, they do not work above 2C).  Should you shear them, it will involve removing head, replacing gasket/head bolts the cost about 240 for parts.  Any diesel Frontera can be remapped for increased performance at very little cost.  2.0/2.2 Diesels  Poor starting from cold or engine cuts out after a few seconds and requires lots of cranking to restart, cause: Injector leak off pipes perished/injector seals.

ECOTEC 2.2 petrol engines eat head gaskets, we have lost count how many repairs we have done in the workshop.  Up side is, cost for a bare exchange cylinder is only 140 if it is cracked.  These engines when fitted to Frontera 4x4 are also prone to cracking exhaust manifolds. (28-04-07)

Any LPG GM is going to be a headache unless you have a four gas analyzer.  Genuine GM duel fuel models being the worst.  Romano gas conversions a better bet (Romano are the only type we fit in our workshop to GM's).  They all eat O2 sensors, even when running OK.  Avoid cheap noble metal replacements, they fail in a very short time.  We can re-program any GM ECU for LPG emulation, dual & single fuel use.  We also recommend and sell BRISK sparkplugs for use with LPG converted vehicles.

Bosch Motronic  ECUs suffer common ignition failures, they are found on Vauxhall Alfa Romeo, BMW, Peugeot cars. It is important to count the number of ECU pins to correctly identify.  Bosch Motronic with 35 (2 row) or 55 pin (3 row) connector.  Bosch Motronic with 88 pin (3 row) connector.  Most failures are with the 55pin ones, which are believed to be made in Eastern Europe.

DIS coil per cylinder system on Vauxhalls and Peugeots (Alfa Romeo & BMW's with 'wasted spark' twin coil system fitted from about 90/92 onwards).  All suffer mechanical damage when servicing plugs!  So check first!  Three cylinder Corsa coil in cap systems are very fragile. 

Note:  GM cars account for nearly half of the diagnostic work in our workshop!  You have been warned.

Battery change on all vehicles with early >2002 Bosch Motronic fuel injection system. May cause fluctuating, excessive idle speed - engine starts after changing the battery.  If the battery is disconnected or discharged the Motronic control units lose their programmed and stored basic adjustments.  When starting the engine after the battery was discharged or disconnected, switch on the ignition for approx 10 seconds and then switch it off again. This makes sure that the old adaptation settings are used.

advice on diagnostic equipment


(date information written)

Page updated 28-05-18