renatodato

My 94 ES 300(ODO: 160,000 miles) suddenly died on the freeway. No sputtering, just died as if I turned ignition off. So far, I've ruled out igniter, fuel pump, timing belt, charging system, crankshaft and camshaft position sensors. When I turn the ignition to the "on" position, there is no "check engine light" in the cluster panel. Scanner unable to connect with computer. Checked all fuses, all OK. I get no spark when grounding the ignition coil/spark plug assembly. I'm thinking ECU/harness problem. Tell me I'm wrong as this will "total" my beloved ES 300. Any help is greatly appreciated. This forum is my last resort. The consensus will decide its fate.

GEORGE_JET

You have checked a lot of the components that would cause this type of problem, but you did not give any details on how you checked it. Did you backprobe the connectors and check voltages? If not, I would strongly suggest doing that. I would also suggest checking power and grd at the ECU. It is very possible that this is a minor problem, but it will take some focused troubleshooting to find the exact cause. I assume that you have schematic and connector pin out. Start at the ECU.

renatodato

Thanks for the suggestion, George Jet. I was going to start at the ECU tomorrow as I just got a hold of the schematic and some test equipment. Some components such as the igniter, ignition coils, both position sensors and fuses, were tested by exchanging them from a working ES 300. Others, like the fuel pump and alternator, were bench tested. The timing belt was checked by peeking through the timing cover while a friend cranked the engine. I'm hoping it's a simple problem but sometimes the simple problems are the trickiest to find. If I get no power to the ECU, does that mean I need to replace it? The dealer suggested buying the whole harness($1500.) since individual connectors aren't sold separately. I'll keep you posted.

GEORGE_JET

Ok, substituting parts is a valid way to isolate the problem. I recommend that you check for power at the ECM. Keep in mind that there are two power feeds, a switched and constant source. With the key on the run position, measure for power and grd. If one is missing you will need to trace it down.

As far as the dealer trying to sell you a harness, DON"T, it is problem is probably a blown fuse or something like that. If you really need a connector, there are plenty cars in wrecking yards that you can purchase connectors

renatodato

Thank You, George Jet. I back probed the connectors and found the connector/wire to the camshaft position sensor frayed and exposed wire on the underside where visual inspection was impossible. Palpation was the key. Went to the local junkyard and found a connector, soldered it, heat shrank-insulated it, changed the blown mini 15 amp EFI fuse and the car runs perfect again. Didn't bother testing the ECM, but it's good to know that it has two sources of power: switched and constant source, which I didn't know. George Jet, you the MAN!

GEORGE_JET

Good job, glad to hear you found the problem without having to spend very much.