Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2005 Isuzu Ascender owners, lightly cleaned up (personal details are redacted by NHTSA).
Driving at night on highway and my exterior lights will go completely off and only my high beams will come on but that's it. They'll come back on usually when I get to where I'm going and park the car but driving on the highway at night and all of the sudden your headlights go out is extremely dangerous. On three different occasions both the high beam and low beams went out. But on most occasions and now every occasion while driving at night the regular lowbeam headlights just go out randomly
It took a while before the electrical issues to progress where they where verifiable with solid symptoms as in transmission faults and poor performance along with loss of communication to steering wheel controls, ac and blower failure, radio etc. The full extent of what is affected and how it will progress as it had to this point is unknown to me or service people. The wiring has been modified and the ignition has been replaced 3 times to try and resolve this issue, and the effects of modification did not work and what that will bring about is unknown at this time. I have notified manufacture, but after I learned of this site and looked at Chevy trail blazer and Isuzu Ascender electrical issues ( same car ), it is clear to me that I am not alone and there is not a known fix for this hardware or possibly software issue. …
I have been having issues with my gas gauge for about 3 weeks...at first I would fill up the tank or at least think it was full as the gauge would move all the way over to full then after I would stop pumping and turn on the car the gauge would go down to 3/4 tank and fluctuate back and forth between 3/4 and full over several days. Then yesterday I went and filled up and decided to not use the gauge as a measuring system and instead just let the pump go until it clicked off as it does when tank is full so I did this and the gauge went up to full then bounced back to empty and now my fuel low light is on and I cannot get any range reading on mileage for gas or anything. Also it should be noted that about that same 3 weeks ago my speedometer stopped working briefly starting off at 65 MPH at rest then it gradually made its way back down to zero at rest and has since seemed to be OK.
Vehicle suddenly 'shuttered' at 65mph on the tollway and the instrument panel failed completely, indicating brake system failure. Concurrently, indicator light for rear drive train also showing failure. Unsure if these issues were related or coincidental. Diagnostics/testing by mechanic resulted in replacement of several electrical system parts, including A/C delco trans selector switch; A/C delco speed sensor; A/C delco ignition switch, and repair of 4-wheel drive engine harness, totaling expense of $808.37. Since repair, no further incident has occurred with these components. While it is clear that would seem related to GM ignition switch recall, there is no published indication that GM SUV's produced under the Isuzu name-plate have been included in the recall, as they should be.
Tl* the contact owns a 2005 Isuzu Ascender. The contact stated that the fuel gauge, speedometer and oil gauge were all providing erratic readings. After refueling the fuel tank, the fuel gauge would provide an erroneous reading of zero. The oil gauge pressure would move back and forth when the accelerator pedal was depressed. The vehicle was taken to a local mechanic for diagnosis and they stated that the fuel pump, sensor and the lever needed to be replaced. The manufacturer was notified and advised the contact to call general motors because the parts were manufactured by general motors. The contact notified general motors but was referred back to the manufacturer of the vehicle. The vehicle was not repaired. The failure mileage was 90,000.
I've been having the same issues with speedometer and gas gauge. I bought the vehicle used and the engine light came on a day after I bought it. The speedometer stopped working as I was driving it off the lot. When back to the dealer and they fixed and it worked for a few months. I have noticed that the speedometer goes haywire when it drops below a certain temperature and the gas gauge when it rains or it's humid. I know it seems ridiculous but I had no problems during the summer months with either up until now rainy season. It has only come off once, when I replaced the battery but it came back on a day later. Hope someone figures something out!
The first time I realized my gas gauge wasn't working, I was sitting at a traffic light. The gas hand read half full. I made the turn at the intersection and the car stopped running. At this point, I had no control over the steering wheel or anything. Traffic was heavy so I wrestled with the steering wheel to coast to the side of the road. Since then, other gauges in the instrument panel have stopped working. Also, my headlights work on bright only. I had the low beams changed and they still don't work. There seems to be a serious electrical issue with this vehicle. With the number of reports, there should be a recall to address these issues.
The vehicle speedometer works intermittently. It will work fine for 5-10 minutes of driving and then does not register the correct speed and eventually stops working all together. I understand this is a well documented problem and that GM is aware of the problems. I contacted Isuzu customer service and was told that a broken speedometer is not "a safety issue." when I questioned that statement the representative did admit that it is a safety issue, but GM is not doing anything about the known problem. A 5 year old car with less than 50,000 miles should not have this kind of problem.
The check engine light( thermostat), speedometer, fuel gauge and now the oil pressure gauge have stopped working or work sporadically and inaccurately. These problems are listed in order of failure and they started at approximately 85,000mi and the last was at 106,000 miles. If I had known this vehicle was made by GM, I would not have bought it. It will definitely be the last GM product in my household. I have had many and all but one had numerous problems. A footnote: a part of the gearshift linkage broke at approx. 95,000mi.
This is regarding my 2005 Isuzu Ascender. While driving on highway i78 in nj sudden noticed that speedometer gauge jumped to 120 MPH but the speed on my portable navigation was showing only 68 MPH. After that speedometer gauge shows 70, 80, 90 MPH or so when vehicle is only at 20, 30 or 40 MPH. Now is passed 120 MPH and not coming back to normal. This seems to be a faulty speedometer. I have never seen any speedometer this way. This is the first time ever facing this issue. Now I have no idea at what speed I am going on.
Electrical complaints in other Ascender years
Frequently asked questions
How common are electrical problems on the 2005 Isuzu Ascender?
NHTSA has 27 complaints about the electrical system of the 2005 Isuzu Ascender, 42% of the model year's 64 complaints. The component named most often is instrument cluster/panel (5 mentions).
Is there a recall for 2005 Isuzu Ascender electrical problems?
No. NHTSA lists no electrical system recall for the 2005 Isuzu Ascender, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2005 Isuzu Ascender electrical problems start?
Half of the complaints with a recorded mileage happened before about 72,000 miles, and 8% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.