Car Wont Start - PIM, VTA1 & VTA2 All highlighted on PFC

[boosted]

The wiring for this is only on the engine harness right. But the short is only within them few sensors supplied from 3i off the ecu?

Yes mate by resistance testing 3i to 4d youve found the short...but the sensors are in parallel so now gotta find which 1.or short on cable...so multi connector etc.

[boosted]

Just a thought...your omp is disabled but presuming switch still plugged in ?

[ttpower]

Hi, so the resistance of.436 is good  between 3i and 4d.
My omp is blocked off and connector just disconnected.

[boosted]

0.436 ohms? I would say no its nearly 0 ohms which is a dead short. tempting to dis connect all sensor on this circuit and see if 5 V present but not sure how much more that voltage regulator can take.

That disconnected plug will have 5v feed ov ground to ecu and switch init...id check that for moisture in the end...ideally that wants sealing up though as a precaution if not the prob. Somewhere in this circuit the  5v is touching the 0V ground. As its an ecu ground it MAY be seperated from the chassis ground but no 100% on that. Its a control circuit not a power circuit so very low amps and v low resistance so need sensor resistances.

As a side note also any recent works on car that may have disturbed something?

[boosted]

Any joy Mate?

[ttpower]

Ok, got back from work late.

Reconnecting the ecu wire 3i with all the sensors disconnected gives me 5v, although if I test 3i with 4d I get around 3v. If I plug in either the map sensor or tps sensor the volts drop to 0.3v.

[ttpower]

Seems with any sensor plugged in its drawing the current pretty much completely and not enough for both, so that a short I think?

[boosted]

Short yes but should be 5v 3I and 4D on loom. which makes me think connector short rather than sensor fault...have you look at that omp connector yet...
youve got 2 v drop just connecting loom...loom me thinks.

Id be happy with 5v on the loom then look at the sensors. With 3v they wont have enough power to work...so im thinking loom!

[ttpower]

Would having the omp disconnected reduce the voltage, should I chassis ground the omp ground wire

[boosted]

No it worked disconnected...check up inside the plug for debris moisture...id be inclined to seperate 5v and ground from this plug...

[boosted]

how id tackle this is.

1. disconnect all sensor from plugs...remove 3I again and check 5v...yes.
2. Connect and confirm 2 v drop and seeing 3v. yes. disconnect.
3. so confirms loom and/or plugs has a short.
4. As omp plug has been hangin down disconnected and all others are sealed this would be the logical place to start. I would identify from drawings 5v feed and ground. 30mm back from plug. cut and tap up. then reconnect 3I and see if 5v.
5. If not then leave taped up..choose another plug repeat process.  
thes ecan be soldered and heat sleeved once fault is found.
if this does not re-instate 5v...where looking at cable in the loom

[ttpower]

The voltage at the ecu is the same when 3i and 4d is disconnected and connected. There is 5v when I ground to the chassis with the multimeter rather then 4d.

All connectors being map, tps and omp have 5v when disconnected, as soon as any is plugged in all sensor connector voltages drop to 0.1

[ttpower]

Traced the ground off the map sensor, goes to front of car, splits in two where one goes the fuel pump relay and the other to the egi relay where the main fuses are.

[ttpower]

Could a relay be causing this, I can\'t see a relay in the drawings though

[boosted]

This would suggest then the voltage regulator is failing under load....so no short circuit although resistance test between 3i and 4d is low! you got 3v or 5v test at any plug end 5v and ecu ground?