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Discussion Starter · #1 ·
I have a 1990 isuzu 2.6L engine pickup that I recently purchased. The check engine light stays on constantly and I researched on how to find out what codes are being stored. When I found where I use a jumper wire to check them, there was already a jumper wire there. I removed the wire but my truck would not turn over without it being installed permanently. Is there a specific reason that someone may have done this for? I appreciate any help in advance.
 

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That's very unusual, the jumper should only be in during 'key ON, engine OFF' code reading process. Having it left in during operation may well have been either; A- the direct cause of your troubles, B- a nay short to 'get it running' & sold... How long have you had the rig & Howe long had the jumper been in?

~psguardian
 

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Discussion Starter · #5 ·
Thank you for the responses. I can start the truck without the clutch but when I remove the jumper, I cannot start it with or without the clutch in. The two wires that are jumpered are black and white I believe. There is also a connector with red and black wires that is danglingm near the steering column as well. I will get a picture uploaded as soon as I can. Thanks again!
 

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Most likely that's the ECM test plug. Mine in my 91 amigo was over in the left kick panel. Once I located it I left it in a little better location. My book is at home so I can't look up any info for you, sorry !!!
 

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Look over behind the plastic kick panel. You should find a plug like those over in amungst the wires. It's kind of long in a coil. I can't remember if it's red/green wires or not. That switch is probly connected in with the clutch pedal. It's not a big deal, just a safety feature that your already aware of.
 

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Discussion Starter · #9 ·
bradzuzu,
Are you talking about the white push button switch? Do you know what wires the jumper wire is connected to? If I remove I cannot start the truck. Thanks
 

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That plug would go to that pedal switch for the clutch. Your going to be looking fir two wire leads that are kind of long and just hanging out in the mess of wires on the far left. I actualy think one will be a female spade and the other will be a male.
 

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Discussion Starter · #12 ·
I connected the jumped connector to the push button switch and realized that the button was broken where the clutch would engage it at. I held down the push button while the I connected the connector to it of the two wires that were once jumped together and it started right up. Now I just need to figure out which ones I need to jump together in order to figure out the check engine light code. It does not have the 12 pin connector type and I looked under the kick panel but unsure which ones to jump. Any ideas on colors over there? I think I may have luckily found a forum of the two colors to jump in the kick panel. red/black and yellow/black. One has a female spade connector and the other has a male. I will try that and update
 

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Discussion Starter · #13 ·
THis forum is the best thing ever. I was able to figure out the which wires I needed to jump in order to read the codes. It shows codes 22 and 25 which I am not exactly sure of where to begin to fix those issues, but I will search this forum up and down and hopefully figure it out. Thanks again everyone who gave me input on figuring out this jumper issue!
 

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DTC - 22 Throttle position sensor error (signal low)
DTC - 25 Intake air temp sensor error (high temp indicated)
 

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Discussion Starter · #15 ·
Shooter,
Thank you for your response. Should I replace both of those sensors or is there a way to check them? Thanks again
 

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There's ways to check them. Got a service manual?
 

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I doubt the chilton has the troubleshooting: The cut off part of last pic (right side)is: Replace ECM





 
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