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1995 Rodeo Isuzu won't start
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wrdavis
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Dec 16, 2007, 7:18 AM
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1995 Rodeo Isuzu won't start
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1995 Rodeo Isuzu 2.6 4 cylinder, Manual Transmission, 2 Wheel Drive, 180,000 miles
Had two problems.
1. Battery was not charging, so I replaced the alternator with a remanufactured one from autozone. This fixed the problem and I confirmed that it was working by starting the motor and measuring the voltage at the battery at 14.5 volts. At this point I was working on a second problem, which is the engine would bogg down when you accelerate. So I was re-adjusting the TPS, replaced the MASS AIR FLOW sensor (and cable, because the connector on the old one had become so bad that it needed to be replaced), and at the same time I was charging the battery, that was low due to the alternator being bad. Once I was done with these tasks I tried to start the engine, but it wouldn’t start. I started to investigate and found that I wasn’t getting spark to the spark plugs. I decided to replace the ignition coil, but still no spark. Upon further investigation I found that I also didn’t have normal voltage readings at the M AP, MAF. I checked all of my fuses and relays and fusible links and they all appear to be good. The only other information that I have is the blower, AC, and charge fuse circuits appear to be dead, both with the ignition on and off (not sure if engine needs to be running). I tried to trace through the schematics, but still no luck. Could this be the ECM or is there something else that I am missing?
(This post was edited by wrdavis on Dec 16, 2007, 7:19 AM)
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DanD
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/ Moderator
Dec 16, 2007, 10:25 AM
Post #2 of 9
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Re: 1995 Rodeo Isuzu won't start
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I just had a look at my power distribution diagrams and I’m going to suggest having another look in the fuse/relay box. Test the fuses with an ohmmeter; late production had a 100 amp early production model a 60 amp fuse that protects the circuit(s) that you mentioned, along with portions of ECM & ignition system?
These are large amperage fuses and would take a dead short to ground from a high amperage circuit. Maybe something like an alternators main terminal; could it have touched ground while replacing the alternator?
Dan.
Canadian "EH"
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wrdavis
Novice
Dec 16, 2007, 5:10 PM
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Re: 1995 Rodeo Isuzu won't start
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I checked the 60Amp Fusible link for continuity and it was good. I just noticed that the check engine light is not coming on when I turn the ignition on. I believe that indicates I am either not getting power to the ECM or a bad ECM. I can't remember if the check engine light use to come on, but it definately is not coming on now. A new light that is coming on when I turn the ignition on is the RrABS light.
(This post was edited by wrdavis on Dec 16, 2007, 6:20 PM)
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DanD
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Dec 17, 2007, 5:37 AM
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Re: 1995 Rodeo Isuzu won't start
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The check engine should be coming on; the ABS light should come on when the ignition is first turned on; for a bulb check and a state of health of the system check, then go out.
With the lights doing what they are; I’m still thinking a power feed problem; it’s not likely those two different computers crapped out at the same time. You said you had wiring diagrams; check what pins of the ECM & ECBM connectors are power feeds and then make sure they have power at them? Either constant or ignition feeds.
Dan.
Canadian "EH"
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wrdavis
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Dec 17, 2007, 9:48 AM
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Re: 1995 Rodeo Isuzu won't start
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The RrABS light does go off after a few seconds, so that is a none issue. I checked the power to the ECM (Red/Wht) and it is showing 12 volts, so it is getting power. I have a feeling what happened is when I cut the wire on the MASS AIR FLOW it might have shorted out the ECM. According to the schematics the MAF has 3 wires and a braided wire connected to the AIR FLOW SENSOR SHIELD. I reconnected all of the wires and the braided wire. The thing that I don't understand is the braided wire ends near the connected end and doesn't appear to connect to the MAF. I do see this same braided wire connecting into the ECM.
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DanD
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Dec 17, 2007, 11:04 AM
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Re: 1995 Rodeo Isuzu won't start
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This braided wire is a shield to prevent interference produced by other electrical devices from entering the MAF return signal wire.
It is only connected to ground through the ECM.
Have you checked for ignition feeds, connector C210, terminals 1 Lt green/red &14 Lt green/black should have power via the ECM relay with the ignition on?
The ECM relay is found in the fuse/relay box and is protected by a 15-amp fuse in the same fuse/relay box.
Dan.
Canadian "EH"
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wrdavis
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Dec 18, 2007, 5:59 AM
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Re: 1995 Rodeo Isuzu won't start
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Still concerned about the braided wire and shield. I don't want to blow another ECM. Could this cause the ECM to act this way? On this vehicle the MAF wires are enclosed in a grey taped bundle. When I cut the wires to splice on the new connector and wire, I noticed a copper type shield where I cut. Is it imperative that the shield be in a certain location and be perfectly intact, or is it just used for reducing electical signal noise? Again I have reconnected the ground, hot and signal wires and the braided wire. I had to replace the connector and wire because the old one was falling apart and needed to be replaced. My current plan is to get a used ECM today and try it.
I previously checked the ECM relay and it is working and the ECM fuse is good. I haven't tested the power at the terminals that you mention yet.
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DanD
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Dec 20, 2007, 5:24 AM
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Re: 1995 Rodeo Isuzu won't start
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It's just a shield and as long as it's not touching an exposed insulated wire it'll be fine.
Dan.
Canadian "EH"
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wrdavis
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Dec 20, 2007, 12:42 PM
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Re: 1995 Rodeo Isuzu won't start
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I replaced the ECM and now everything is working great again. I would like to thank everyone for their responses.
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