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Auto_Enlightenment, ASE Certified Technician
Category: Car
Satisfied Customers: 237
Experience:  ASE Master Certified Technician
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Isuzu Rodeo: My 1995..It blows it intermittently when in forward gears

Resolved Question:

My 1995.5 Isuzu Rodeo 3.2L A/T is blowing the Engine Device Fuse. It blows it intermittently when in forward gears. Pulled Range Mode switch (neutral safety) and cleaned. Same issue. Put new one in with no change. Unplugged EGR valve and purge valve and continued to blow fuse. Switched relays for ECM and continued to blow fuse. Weird thing is that it will not pop the fuse in neutral, park, or reverse despite changing RPM's. Sometimes the truck can be driven for few miles with no issues then will blow the fuse. Other times it pops it as soon as the ignition is turned over. Altenator was replaced 25k+ miles ago and is putting out 13v or so when running. Everything electronic is working. No obvious signs of bad wires anywhere. Has the Winter/Power switch that lights up on dash when fuse is good. Both options work as well. However, the Winter mode never worked before this issue. The light would light up on the dash when the key was turned over but the switch would not engage it. Only Power Mode worked. Now both are operational. Worse part of this is my vehicle is stranded 400 miles away and I'm trying to fix it through someone who is growing very impatient with it. I'm running out of options and am wondering if its as simple as a faulty voltage regulator in the alt or if its deeper. Any more suggestions so I can make a list? Thanks!
Submitted: 5 years ago.
Category: Car
Expert:  Auto_Enlightenment replied 5 years ago.
My apologies, Chat mode was not responding so I had to switch to this Q&A format.

I would like to help with your problem but need to do some research first. Can you tell me the fuse location, number, and amperage? A fuse will blow if the circuit is being overloaded or is shorted to ground somewhere. Have any accessories been installed prior to this fuse showing problems? If nothing has changed on the vehicle then I would suspect the problem is the power being shorted to ground somewhere on that fuses circuit.
Customer: replied 5 years ago.
It's a 15amp marked as CB-3 in the dash. No new electronics installed recently. Only a new battery, alt, power window actuators, and trailer harness over 20k miles ago. The harness did give me troubles earlier this year, causing a blown fuse that threw my transmission into limp mode but that's been resolved.
Expert:  Auto_Enlightenment replied 5 years ago.

We need to start by tracing the wires back from all of the highlighted components in this diagram. If you unplug all of these components and the fuse still blows then the power wire to one of them is shorted to a ground somewhere.



Let me know what you find here then we will proceed if needed. Thanks.

Customer: replied 5 years ago.
Unhooked EGR, EVAP can, and switched relay with same results. I'm assuming the shift indicator on the diagram refers to the Neutral Safety Switch aka Range Mode Selector? That's all been pulled, cleaned, reinstalled, then replaced with same results. All wires in shifting column itself are good. That leaves me with the alt. Also pondering if the pre-cat O2 sensor is bad and shorting. Continue digging this evening.
Expert:  Auto_Enlightenment replied 5 years ago.
The o2 sensor does not get its power from that fuse, only the highlighted components are powered by that fuse. If you unplug all of those components at the same time and the fuse still blows then a wire is shorting out somewhere. I will be online tonight so I will follow up with you then to continue diagnosing this problem with you. Thanks.
Expert:  Auto_Enlightenment replied 5 years ago.
Hey, just wanted to check in to see if you've had a chance to mess with the Rodeo. If there is absolutely anything I can so to assist, don't hesitate to ask.
Customer: replied 5 years ago.
Waiting on a new alt now. Unplugged the old one and it wouldnt blow the fuse. Soon as it was plugged back in, fuse blew soon as key was turned.
Expert:  Auto_Enlightenment replied 5 years ago.
Great, I'm glad you got it figured out without having to chase down some shorted wire hidden somewhere Laughing.

Your Positive Feedback is greatly appreciated. Thanks.
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Expert:  Auto_Enlightenment replied 5 years ago.
Thank you for allowing me to assist with your repair, it was a pleasure to work with you!

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