I ahve a 1990 240DL - is there an ECU and Power stage and Ignition module? Where are they located?

Power stage and ignition module (Left side fender behind battery) are different name for the same thing. Not easily tested, they do fail. ECU (buried up in the dash drivers side) does not fail so often.

If you have a problem it may be easier to help by knowing the symptoms.
--
David Hunter

The power stage is behind the left headlamp.
--
Art Benstein near Baltimore

What does the power stage do and how can you test to see if it is faulty? Thank you

1. key off position.

2. Disconnect wiring harness connector to ignition power stage module (same part as test # 1)

3. Red test lead to terminal # 5 of connector and black test lead to ground.

4. Have a helper try to start the car.

5. Meter voltage should show about 2 volts.

6. Stop test. Key off.

7. Reconnect wiring harness connector to ignition power stage module .


This tests the signal from the Ignition ECU. It helps to narrow the diagnosis or problem area. At least t it is supposed to (another story entirely with Volvos).

diyer

With hey on and engine NOT running, there should be battery voltage between terminal # 4 (+ red colored test lead) and # 2 (- black colored test lead).

You need a test meter that does volts and continuity, so a multimeter will suffice for testing this voltage.

I did this test recently. Hard part is getting the lead tip in up side down as it needs to all be connected when you test it. So, unhook your battery clamps. The take the power stage connector off. Pull the harness rubber boot back. Break off a aluminum paper clip in half and put the halfs in the back of the connector at numbers 4 and 2 terminals. Then put the connector back on, put your battery cables back on, turn key on with dash lights on, but engine off, and then test for voltage. I also did a continuity test on all my terminals just to see if there was at least some continuity there. Take your time. Where are you located? ... I can do the test for you if you are close to me.

Philadelphia, PA -- diyer