My first post, I did some searching and came up with a couple similar problems, one guy never said what happened and the other guy spent $600 having a mechanic fix it.

If it matters, the Amigo is a 4x2 S but has the 31x10.5 tires factory. I've considered converting it over to 4x4, but in Oklahoma, I really don't need it. I live in the Oklahoma City area and there aren't any great 4x4ing places that I know of, plus I'm kinda into drag racing and don't have the funds to do that, let alone build a 4x4.

Anyways (this could get long), I was driving my Amigo to work one morning a couple weeks ago and heard a loud pop (like if you dropped a C4 christmas lightbulb on concrete) which seemed to originate somewhere behind the guages on the left side. Almost all the lights that come on when you first turn the key on to start the vehicle came on. The truck seemed to loose a bit of power (which I now know was the 'limp mode'), but still ran and I was about 1/2 mile from the office, so I drove it on in. Sitting at a stop light, it acted like it wanted to die and I had a surging problem that I've had before.

I offhanded figured out the surging problem was due to low coolant level in the radiator because once I filled it up, it went away. I never checked any plugs, the truck doesn't drip anything, but I slowly loose coolant over several months.

I tried starting it back up once in the parking lot, and it started, but the lights all stayed on, and I turned it off. After work, I went to try and start it and it'd run for a couple seconds, then die like the fuel pump was shut off.

I borrowed the boss's truck, went home and got a trailer and came back to load the truck up. I could put it in 1st, start it, dump the clutch and get it rolling, but there was no way I'd get it up on the trailer. I trying keeping the key engaged and it'd stay running, although still engaged to the starter, but I discovered if I held it about halfway between, it'd run, albeit like it did after the pop. I got it loaded and home, but had to let it set for several days as I was working a lot.

Talked to several friends, a couple who are mechanics and they thought it might be the starter switch in the column. I picked one up at Pull-A-Part for $10 (domestic switches are $5, shoulda told 'em it was for a S-10) out of a '94 (I think) Rodeo or Passport. The other morning I tried putting it in. It plugs in at the bottom, but the top isn't shaped right to fit in, I went on in to work and thought, "Hey, just use the switch to start it" and when I got home, I tried that, didn't work.

I took the guages out and looked around there, nothing smelt burnt and I couldn't find anything wrong. It does the same thing with no gauges plugged in, so there's nothing in there that's causing the problem. I have a dealer manual for the '90 Amigo, and I looked in there, but couldn't find anything that helped.

Well, last night I found the section I should have been looking in and found out the ECM is in the kick panel and has a jumper for codes. With the key in the 'on' position, I only get the obligatory '12' code and the code '41' which says it has to do with the crank position sensor that's in the distributor. I cleared the code out, the truck still runs the same way, but the code hasn't come back. I called around for a new distributor, OReilly's has, I assume, a rebuilt one for $243. Pull-A-Part didn't have a 2.6 in stosk, another parts yard has a couple,and they want $100 for a used one. After reading the one guy's delima where he replaced the distributor and it didn't fix the problem, I'm a little leery about throwing more money at it until I get a better handle on if its that or the ECM.

The confirmation that it runs with the key halfway between run and start proves it's not a fuel or air issue, or even a ground issue I don't think and the coil is working. It would seem its something that sends a signal somewhere that's the problem. I can try cleaning the speed sensor as someone mentioned in one of the other posts, but other than that, I'm sort of at a loss.

Smiley. . .? . . .you move to OK...?






this has got to be the switch. have you tried just jumpering it?
welcome, btw

The pop and all the lights coming on makes it sound like the alternator belt brok off while driving.

When my alternator belt broke on me driving down the highway, I also heard a thump and all my lights lit up. It still drove ok, and I was able to make it to an exit on battery power alone. Lucky for me I had a spare and found an auto parts store in a town off the highway.

I personally doubt its your distributor and think the first place to look would be the alternator.

yeah, i'd go for the alternator, too.
paragraph #3 sure points that way...except for that POP behind the dash...

and except for the key halfway thing...(which still sounds like ignition switch

or...

doesn't the fuel pump run off one circuit from the start position and then switch to another from the run position? maybe the half-and-half is getting the best of both worlds, and it's really some relay?




my new signature:
i love a good intermittent electrical challenge. . .especially when it's someone else's. <img src="/forums/images/graemlins/smile.gif" alt="" />

Nah, I guarentee it's not the alternator belt.

The new switch does exactly what the other switch did, even though it's used, what are the chances of both doing that? The windshield said 'bad tranny' on it, so I don't think that's why it was in the salvage yard.

I've tested all the relays and yes, it does go from one circuit to the other, or at least skips either the crank position sensor or the crank speed sensor, but it does either of those in the ECM I believe.

Check the alternator output. If the alternator is not charging the fuel pump only runs while cranking the starter.

Doesn't quite fit your symptoms though.

I'm down with the alternator also...

in addition, it sounds as though the coolant loss might be indicative of a head gasket problem. Do a cylinder leak-down test.

Don't mess with the distributor yet. When the alternator went out on ya, it may have induced a "surge" or "spike" in the electronics that made the ECM think there was a problem with the CPS.

The pop sound ? no idea... unless it was one of the diodes in the alternator "grenading" ?

Yeah, but if I hold the key where the starter isn't engaged, but the key isn't back to the start position, the vehicle runs. I mean, if I didn't have to shift the 5-speed and my hand didn't get tired, I could drive it to teh store and back, so the alternator output doesn't seem to hold water. I had it running 3 or 4 minutes after I had cleared the codes thinking it might bring back the '41'. Usually, the start feature on the fuel pump runs the pump about 2 seconds to bring the fuel pressure up to operating pressure and once the engine is running, the fuel pump runs normal.

Remember, it isn't running quite the same, although maybe if one of the fields in the alternator went out. I can take the alternator out and have it tested at O'Reilly's or Autozone easily enough and that's free. In any case, it'll eliminate a possibility, although I'd be happier if it were the alternator as opposed to the distributor or the ECM.

I'm thinking along the same lines. The truck has 195k on it, I was hoping to make it to 200k and then rebuild the shortblock, likely over this next winter. During the winter, even with 20w50 I get a lower end rattle until the pressure gets built up, then it goes away. I've been hoping to get a 2.6 and rebuild it, that way I can swap it out in a weekend after I get the engine rebuilt.

Don't forget that there are multiple contacts being made in that switch. It could just be that holding it half way is allowing the fuel pump to still be energized in the "start" mode, but the starter motor circuit had already been released. The fuel pump circuit may be a "make before break" circuit, where it makes contact with the running circuit before it breaks contact with the starting circuit.

Make sure they check the output on that auxiliary terminal on the alt when you have it checked. That terminal (marked "L" I believe) is the one that controls the fuel pump and main relay.