The 1991 Isuzu IMPULSE carries 1 open NHTSA recall — most recently covering air bags. Owners report 3 recurring issue clusters, led by “ECU/ECM failure and replacement.” Isuzu stopped selling passenger vehicles in the United States after the 2008 model year, though its commercial truck business is still here, which means parts and knowledgeable service have not disappeared the way they did for some discontinued brands. One item matters more than everything else on this list. The 3.2 and 3.5 liter V6 in the Rodeo, Trooper, Amigo, Axiom, and VehiCross uses a rubber timing belt, and on the double overhead cam versions a broken belt bends valves. If you own one of these and cannot document the last belt change, that is the first call to make. The later models are easier: the Ascender is a Chevrolet TrailBlazer, the i-280 through i-370 are Chevrolet Colorados, the Hombre is an S-10, and the Oasis is a Honda Odyssey. For those, the donor brand's parts and specs apply.
AIR BAGS
Campaign #92V091000 · Jun 7, 1992
Issue: THE STEERING WHEEL CENTER HUB CAN FRACTURE DURING CERTAIN FRONTAL AND NEAR FRONTAL VEHICLE COLLISIONS.
Risk: FRACTURING OF THE STEERING WHEEL HUB CAN DECREASE THEDRIVER'S CONTROL OF THE VEHICLE AND COULD REDUCE THE CRASH PROTECTION OF THESTEERING SYSTEM AND THE DRIVER'S SIDE AIR BAG.
Fix: A STEERING WHEEL REINFORCEMENT PLATE AND NUT WILL BE ADDED TO THE STEERING WHEEL HUB.
What drivers and federal regulators have officially reported about the 1991 Isuzu IMPULSE.
ELECTRICAL SYSTEM
4 NHTSA complaints · 1999-10 → 2004-04
“I HAVE A 1991 ISUZU IMPULSE AND IT'S HAVING ECU PROBLEMS”
“THE CONSUMER STATED THAT THE VEHICLE IS EXPERIENCING THE SAME IDLE CONTROL PROBLEMS AS STATED IN PREVIOUS RECALL REGARDING THE ELECTRONIC CONTROL UNIT”
“FAILURE OF INTERNAL CPU CONNECTIONS CREATES FAULTY IDLE AND DRIVEABILITY”
VEHICLE SPEED CONTROL
8 NHTSA complaints · 1999-07 → 2002-06
“THE SYMPTOMS OF THIS FAULT ARE MOST NOTABLY ERRATIC IDLE, IDLE REVVING AND DROPPING, IDLE DIPPING OFTEN WITH ENGINE DYING, IDLE HANGING HIGH ABOVE 2,000 RPM, AND ENGINE DYING OR STALLING FOR NO REASON WITH NO TROUBLE CODES”
“WILL PUT THE CAR INTO HIGH IDLE AT ANY GIVEN SPEED AND WILL NOT RESET UNLESS CAR IS TURNED OFF AND RESTARTED”
“CAR RACES ENGINE BADLY IN THE SUMMER WHEN TEMP OVER 80 DEGREES-WONT IDLE”
ENGINE AND ENGINE COOLING
6 NHTSA complaints · 1999-11 → 2001-07
“THE CAR WILL FOR NO REASON STALL, EVEN AT HIGH SPEEDS RESULTING IN A LOSS OF POWER STEERING AND BRAKES”
“WHEN CAR WARMS UP YOU CANT DRIVE OR IT WILL STALL”
“THE VEHICLE FAILS TO RUN AFTER IS WARMS UP”
Note: NHTSA also opened 1 defect investigation(s) on this vehicle that closed without action.
Issues on other model years
Source: NHTSA Office of Defects Investigation (ODI). Complaint data refreshed Sep 20, 2026. Investigation data refreshed Sep 1, 2026.
We display NHTSA's record with attribution; we don't editorialize on what these complaints mean for any specific vehicle.
Critical for safety and preventing major damage
Replace every 75,000 miles or 7 years on the V6 in the Rodeo, Trooper, Amigo, Axiom, and VehiCross. Do the water pump, tensioner, and idlers in the same job, because the labor is nearly all in the access. The double overhead cam version is an interference design, so a failed belt means bent valves rather than a tow. The 2.6 four and the GM and Honda sourced engines in the later rebadges use chains and are not on this schedule.
Estimated cost — typical U.S. ranges
Dealer
~$935–$1175
Shop
~$655–$825
DIY
Pro only
On interference engines, a snapped belt destroys valves. Worth doing on schedule. Bundle water pump + tensioner — labor is already there.
Isuzu specified 3,750 miles under its severe schedule, which covers towing, short trips, and dusty roads. On engines this old, stay near that number and change at least once a year regardless of miles.
Estimated cost — typical U.S. ranges
Dealer
~$120–$160
Shop
~$85–$115
DIY
~$25–$55
Full synthetic costs more than conventional. 5-quart 0W-20 + filter is the typical bill.
Rotate every 7,500 miles. On the Trooper, Rodeo, and Amigo, check the tailgate-mounted spare as well. Sun exposure ages it faster than the four tires carrying the truck.
Estimated cost — typical U.S. ranges
Dealer
~$85
Shop
~$60
DIY
Free
Often free at the shop where you bought the tires — worth asking before paying.
Inspect pads, rotors, hoses, and hard lines at every service. These are heavy body-on-frame trucks with rear drums on many models, and drum hardware seizes on vehicles that sit.
Estimated cost — typical U.S. ranges
Dealer
~$85
Shop
~$60
DIY
Free
Most shops do this free as a courtesy with any service. Don't pay separately if you can avoid it.
Replace every 2 years. On a truck this old it is the cheapest way to protect the master cylinder, the calipers, and the ABS unit.
Estimated cost — typical U.S. ranges
Dealer
~$180–$200
Shop
~$125–$140
DIY
~$10–$25
DOT 3 or 4 — match the cap. Vacuum bleeders make this a one-person DIY.
Keeps your vehicle running smoothly and efficiently
Change every 30,000 miles, and right away after any deep water crossing. Front and rear differentials and the transfer case each hold their own fluid. Limited-slip rear axles need the friction modifier added when refilled.
Estimated cost — typical U.S. ranges
Dealer
~$105–$140
Shop
~$75–$100
DIY
~$15–$40
AWD/4WD vehicles only. Easy drain-and-fill on most platforms.
Drain and fill every 45,000 miles, or every 30,000 if you tow. Fluid spec follows the drivetrain: Isuzu or Dexron III for the original models, Dexron VI for the GM based Ascender and i-series, and Honda fluid for the Oasis.
Estimated cost — typical U.S. ranges
Dealer
~$330–$500
Shop
~$235–$355
DIY
~$60–$180
Some sealed transmissions have no dipstick — fill is precise and best left to a shop. Many drivers can still DIY drain-and-fill.
Around 60,000 miles on conventional plugs, up to 100,000 on platinum. Rear bank access on the V6 is tight, so this is often worth pairing with other top-end work.
Estimated cost — typical U.S. ranges
Dealer
~$285–$390
Shop
~$200–$275
DIY
~$25–$100
Iridium plugs cost more but last 100k+ miles. V6/V8 access varies wildly — some are tough.
Replace every 30,000 miles, or every 15,000 if the truck sees dirt roads or trail use.
Estimated cost — typical U.S. ranges
Dealer
~$60–$95
Shop
~$45–$70
DIY
~$15–$40
5-minute job on most cars; the airbox lid usually has clips, no tools needed.
Extends the life of your vehicle and improves comfort
Every 3 to 5 years. If the timing belt is being done, do the coolant at the same visit, since the water pump comes out either way. Ask the shop to check the radiator and heater hoses while it is drained.
Estimated cost — typical U.S. ranges
Dealer
~$285–$330
Shop
~$200–$235
DIY
~$25–$60
Use the manufacturer-specified coolant — wrong color/chemistry can damage the cooling system.
Test the battery and alternator once a year and clean the ground straps. Frame grounds corrode on trucks of this age and cause faults that look electrical but are only dirty connections.
Estimated cost — typical U.S. ranges
Dealer
~$225–$390
Shop
~$160–$280
DIY
~$130–$250
Most auto-parts stores test and install batteries free with purchase. Skip the dealer markup.
Typical U.S. ranges. Actual quotes vary by shop, parts choice, and vehicle condition.
How we estimate: Dealer = OEM parts × 1.4 + labor × $165/hr. Shop = parts + labor × $115/hr. DIY = parts only.
This maintenance schedule for the 1991 Isuzu IMPULSE reflects Isuzu's published service intervals. Your actual service needs may vary based on driving conditions, climate, and vehicle usage. Always consult your owner's manual for model-specific recommendations.