QuestionQUESTION: I have a 91 4Runner with a 3.0 V6 & auto trans. I've owned it for a week and was driving down the road when it just quit, like someone turn the key off. I coasted to a parking lot and tried to restart it but all it would do is crank. I noticed that there was no ck eng lt on with the key in run position. The next day I did some checking and there is no spark at the plug or coil. I did a resistance ck on pick-up coil & coil as well as ck powers. All looks good in those areas. I checked the fuses for the EFI, Gauges, Ignition and all were good. I then did a test on the purple wire for the ck eng lt by grounding it and the ck eng lt came on. According to the flowchart it said to try another ECU which I did but nothing changed, still no lt & no start. I tried to read any codes but the ck eng lt will not flash. I checked powers & grounds at the computer and all seemed good except for the grounds. When I ck the E01, E02,& E1 with the terminal disconnected they read 20 ohms. I ck the E1 connector at the test terminal under the hood & it read only .05 ohms. I know these tie into some sensors as well. Is this the reason they read high. Maybe I'm not testing these right. I even went as far as to slave in a new ignitor & that didn't work. Any help would be great.
ANSWER: By grounding the purple wire it provided a ground path for the check engine light, this wire goes directly into the computer which is supposed to provide a ground when there is a malfunction and when the key is turned on, check this wire from the light to the ECU for continuity,to see if the wire may be open, The E1 terminal should be ground so the reading there is good, the other terminals should show some resistance because you are reading resistances of some of the components in the circuit.
Check to see if the timing belt is not broken, remove the distributor cap, does the rotor turn when the engine is cranked over? If that's the case then I would recommend replacing the distributor, I have seen quite a few cause a no spark condition even though the resistance checks were good. You can probably get one at a salvage yard just for test purposes but I'm pretty sure that it will solve the no start issue if the timing belt is ok.
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QUESTION: I tried a salvage distributor assembly and still have no spark. The timing belt was changed shortly before I got the vehicle and the rotor does turn. The wire going to the ck eng lt is good. I still have no ck eng lt when key is in run position. Still can't read codes when you jump the connector. The lt doesn't do anything. I don't see an alarm in the wiring diagram so I'm assuming there isn't one. Would an alarm shut the ignition down like this? If it does that doesn't explain the ck eng lt not working. Any other ideas would be great.
ANSWER: If it has an aftermarket alarm system installed it could cause a loss of spark, check under the dash on the left to see if there is evidence of an alarm system, if so I would advise removing the entire alarm system and restoring the ignition to it's original form.
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QUESTION: Well I checked for the alarm and didn't see one installed, so back to square one. I guess I'm baffled why the ck eng lt will not come on with key power. I did try to ck the injectors with a noid lite but they didn't pulse either. I'm assuming it's because it's tied to the no spark issue. I just can't seem to figure this one out. Any other ideas would help. Thanks
AnswerI know that you said that you tried another ECU but everything you have told me points directly to an ECU problem or a possible wiring problem, if the injectors have no pulse signal this confirms this as a possibility, if there is no spark you will not get an injector signal because the computer has to see the IGF(spark) signal or the injectors will not be commanded to turn on, the IGF signal comes from the igniter which in turn gets this from the distributor, the check engine light not turning on and not being able to get any codes from the computer point directly to either a computer or wiring problem, start checking some of the wiring underneath, especially the wiring to the O2 sensors, I have seen cases where the wires were corroded at the connectors, it may be necessary to open the wire harness insulation to check for problems, this is a little more complicated than just replacing a part or two, there is something wrong with the wiring.
