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 Weird problem with 90 LWB ECU
#1043797
03/12/12 10:03 PM
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Joined: Feb 2001
Posts: 1,992
OP
Body Damage is Cool
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Gang, I have been searching for an ECU for my wife's uncle 90 LWB ECU. The original ECU blew/ burned some resistors with a good display of smoke. Oddly enough, the truck will crank and run with the smoky ECU. Well, after some searching my wife uncle got another ECU. He installed it and guess what? it also went up in smoke burning the same resistors. <img src="/forums/images/graemlins/zombie.gif" alt="" /> I have not seen the ECU to guess what might be causeing the problem and my best guess is an issue with some shorting wires. But have any of you ever experience the same? Javy
88 red Montero with the Dakar Special Edition decals, 438,000 miles (As of 7/23/2012) some occational blue puffing but still strong and counting!!! I am going ppsshhh (turbo), Stay tuned =) ...
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 Re: Weird problem with 90 LWB ECU
[Re: JAVYPRO]
#1043798
03/12/12 10:16 PM
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Joined: Feb 2001
Posts: 9,781
Mitsubishi Forum Moderator
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I thought we talked on here about whether a shorted out idle control motor could cause the ECU to short, but that might have been a discussion related to one of my other vehicles.
My guess is that it is a short somewhere in the system, either a sensor itself or a sensor wire path maybe?
DougH
1997 SR - Current Lawn Ornament
1995 SR - RIP
1993 RS - RIP
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Re: Weird problem with 90 LWB ECU
[Re: DougH]
#1043799
03/12/12 10:20 PM
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Joined: Jan 2000
Posts: 16,227
Web Wheeler
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One of the places that repairs ecu's mentions that a damaged IAC/ISC can ground out the ECU causing it to also become damaged.
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Re: Weird problem with 90 LWB ECU
[Re: off-roader]
#1043800
03/17/12 01:26 PM
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Joined: Feb 2001
Posts: 1,992
OP
Body Damage is Cool
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One of the places that repairs ecu's mentions that a damaged IAC/ISC can ground out the ECU causing it to also become damaged. That might explain why it will still run. We got plans to tear this thing up today, that is why I cannot be with y'all at the N GA run. Lets see what we find. Thanks Javy
88 red Montero with the Dakar Special Edition decals, 438,000 miles (As of 7/23/2012) some occational blue puffing but still strong and counting!!! I am going ppsshhh (turbo), Stay tuned =) ...
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Re: Weird problem with 90 LWB ECU
[Re: JAVYPRO]
#1043801
03/17/12 11:45 PM
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Joined: Feb 2001
Posts: 1,992
OP
Body Damage is Cool
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Well here we are beating it. We checked the ISC as per the FSM and it is within specs.
Between connectors 1&4 it calls for 3.5-6.5 Kohms and we are reading 5.3.
Between connectors 1&3 the resistance should change smoothly and it does.
Connectors 1&2 with a depressed pedal it should read:non-conductive and with released: conductive.
So, the ISC is within specs. Next step? Wiring and it is doesn't look fun at all.
Javy
88 red Montero with the Dakar Special Edition decals, 438,000 miles (As of 7/23/2012) some occational blue puffing but still strong and counting!!! I am going ppsshhh (turbo), Stay tuned =) ...
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Re: Weird problem with 90 LWB ECU
[Re: JAVYPRO]
#1043802
03/18/12 10:33 PM
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Joined: Feb 2001
Posts: 2,356
Body Damage is Cool
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Where do the wires go? I would expect they would go to the ECU. I don't have a wiring diagram in front of me. Can you disconnect the ECU plug and run the same checks? This might help isolate a bad wire of connector between the ISC and ECU. Just my $0.02.
Mitsu # 6 - 98 6G72 Montero Sport, Locking Rear Diff, Aisin Manual Hubs, 31x10.5
Mitsu # 7 - 02 6G74 Montero Limited
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Re: Weird problem with 90 LWB ECU
[Re: MarkG]
#1043803
03/19/12 11:41 PM
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Joined: Aug 2004
Posts: 644
Rock Warrior
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Where do the wires go? I would expect they would go to the ECU. I don't have a wiring diagram in front of me. Can you disconnect the ECU plug and run the same checks? This might help isolate a bad wire of connector between the ISC and ECU. Just my $0.02. Yep disconnect the ecu and run the same test from there. be sure the isc is connected.
Over the hill but still climbing.
88 Montero 2.6L auto, manual hubs, cooling fan conversion gps,recurved distributor,LSD Diff.
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Re: Weird problem with 90 LWB ECU
[Re: JAVYPRO]
#1043804
03/21/12 12:51 AM
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Joined: Jul 2003
Posts: 850
Rock Warrior
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Javy, don't know if you've seen this. Went though this about four years ago on my Sport. Testing it doesn't mean it's working. Mine tested within spec, too, but it still wasn't working correctly. DSMIAC Automotive - IAC/ISC SiteEnded up getting my replacement from them. Helpful bunch. Edward
'97 Montero Sport LS 5-Speed 3.5L conversion
SAS Dana 44s & ARBs, 35" Yoko Geolandar M/Ts
NP231 B4R doubler/Terra Low231/RP 5.38 229:1
'99 Montero Sport Limited 4WD SAS 3-link project
'03 Montero Sport Limited AWD
'97 Montero Sport LS 5-Speed 4WD
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