OK so I've got both injector fuses good. I've got 12 volts at the injectors, but my noid lamp shows no ground signal from the ECM when cranking (no flashing). The rev counter jumps to around 500 rpm so I guess my ICM is OK. I can hear the injectors firing if I manually ground them. Also ( and this is where I'm confused) if I ground either bank of injectors it grounds ALL of them - surely it should only ground that bank?

I also have one bad injector - doesn't fire and has only about 1.5 ohms resistance, all the others are around 15 ohms. (All measured directly at the injector)

I think my ECM may have fried the injector drivers and have another ECM coming, but not here yet.

Anything else to suggest - thanks for ANY help!

ECM won't ground injector(s) till first see reference signal from ignition.

See my Cave, HE Ignition and ECM Heat

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Yes I know, and have checked that the rev counter moves when cranking so there is an ignition signal.

Also I still don't understand the strange effect of grounding all injectors at the same time.

Thanks for the message

Pull the harness connectors from the ignition control module and be sure the contacts are fully visible. Sometimes they strike the module pins and get pushed back inside the harness. On a couple of occasions I've found that to be the cause of a fuel pump not running. If the right one gets pushed back, the ECM won't see a reference signal, as Ogre pointed out.

Thanks - I've done that and everything seems OK.

Any comment on my grounding issue?

I've seen harnesses where the cross wire the two injector outputs. I am sure that is why you are seeing one injector bank grounding the other.

Does the ECM have power?

If the ECM has power it will light the SES light key on engine off.

If it is getting power the ECM will turn on the fuel pump relay for two seconds when you first turn the key to on but don't crank. Note this test does not apply if the key hasn't been off for at least 45 sec so don't take alarm if it doesn't do the test in rapid succession.

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Does the ECM get ignition pulses from the ICM?

After the ECM has passed the above two tests then just bump the starter. Don't crank it since that will close the fuel pump relay and confuse the test. Just turn it to crank enough to barely start to engage the starter. Since the engine turned at least 1/3 rotation the ECM should have seen an ignition pulse and the ECM should again turn on the fuel pump relay. The relay should stay on for two seconds and then turn off. If it does that then the ECM is getting ignition pulses from the ICM.

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If the ECM is working, and is getting ignition pulses but not firing the injectors - It still could be a TPS problem. If the ECM is reading the TPS as 100% then the ECM is programmed not to fire the injectors. This is only during start up. Unplug the TPS to see if this is potentially the problem.

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If none of the above then I would replace the ECM. Make sure you swap your PROM from the suspect ECM into the replacement ECM.

[This message has been edited by phonedawgz (edited 06-12-2014).]

Thanks for the helpful reply.
SES is On with key on.
Fuel pump relay runs as described, but still no injector signal.
Sorry to be stupid but how do I unplug the TPS?

I've disconnected the injector harness at the 6 way connector and there is no "cross wiring" in that section from connector to the injectors. I'll disconnect the ECM and check that harness as well. Could the common ground happen in the ECM if the drivers are dead?

THX again!