My 1991 Nissan 240sx won't start - it won't even try to turn over. This one is a real mystery; I think it must be the starting circuit, so I'm trying to go through the service manual carefully and check everything. However, I still can't find the issue. Does anyone have any ideas? Details inside on what I've tried so far.
My car is a 1991 Nissan 240SX fastback with manual transmission. When I turn the key to "on," the instrument lights come on and the seat belt bell dings as usual. When I turn the key to "start," the lights dim a little but nothing happens – no rev, no turning, no nothing.
I have owned this car for about six months. It's in relatively pristine condition for a 1991 vehicle: it only has 95,000 miles on it, all of them with a single owner who took immaculate care of the vehicle. (Even minor details are in surprisingly good condition.) In general, it has run perfectly in that time. I have had minor issues with starting it before, however. Sometimes it wouldn't start because the clutch pedal wasn't all the way down – there is a clutch interlock switch, so the starter won't start unless the pedal is down. By last week, this was happening pretty much every time I started it; but the solution was pretty simple: I picked up the pedal and tried to push it down a bit further to engage the switch, and it would start right up. But last week, I tried this and discovered that it didn't help – the car wouldn't start at all.
The story so far:
At first I thought it must
be that stupid little clutch interlock switch. I checked and found that it was indeed not being depressed when I pushed down the pedal. But – even when I depressed the switch, the car wouldn't start. So I thought maybe the switch was faulty; I ripped it out and just wired the two ends together. Still nothing. I thought maybe the switch broke rather than connected a circuit; so I tried disconnecting the two ends. Still nothing. Hm.
At this point I was starting to get puzzled about what was wrong, so I pulled out my service manual and got to thinking. For reference, here is the service manual's wiring diagram of the starting circuit.
Since the thing isn't even cranking, I think something in this circuit must be bad.
My steps so far:
1. I started with the battery. The lights come on fine and everything, so it wasn't likely, but I pulled the battery and brought it to Autozone for testing / charging. But it has a full charge, and is good.
2. I checked all fuses and fusible links. All of them are good. I even replaced the clutch relay fusible link, just in case there was something wrong with it that I wasn't seeing. No dice - still nothing.
3. After that in the circuit is the ignition switch – so I thought about this. I'm pretty sure that the ignition switch is working, since the lights come on when it's at "on" and dim a little when I turn it further to "start." So I think that's not the problem.
4. Next is the clutch interlock relay. I have heard that those can go out pretty easily, so I spent the twenty bucks and replaced it. Still nothing.
5. Clutch interlock switch – I've ripped this out; it doesn't seem to be the problem.
6. The starter motor – I don't think this is it, since I'm not getting any noise at all when I try starting.
I've tried looking at the harnesses, too – they're in great condition, no visible shorts or anything.
Does anybody have any idea what might be going wrong here? I'll be around to answer any questions you might have, and I can post pictures of various things if you want. This is a real puzzle for me.
I also feel like the next thing to do must be to test this with a voltmeter. I've got one, but I don't really know how to go about this. My first impulse is to make sure electricity's getting to the starter; but I'm not sure where it's supposed to come from. I tried testing the main wire that goes into the starter, but it has a charge on it even before I turn the key – which seems weird.
(And I'd like to be able to go home for Christmas, so if you help me out I'll be eternally grateful. Thanks in advance!)