Police Mode Activated: Jeep Grand Cherokee 5.9 Limited

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These days, SUVs are taking over the performance category once occupied by affordable performance sedans like the Ford Contour SVT, the Chevy SS, and the Nissan Sentra SE-R, among others. What makes that incredibly ironic is that Jeep built a hot-rod Cherokee years ago that made enthusiasts and road test editors ask “Why?” in perfect unison. However, a thoroughly quick SUV is no longer an oddity, making pioneers like this Jeep Cherokee 5.9 Limited here on eBay one of the quickest crystal balls ever made.

This particular example is listed by a seller that sounds knowledgeable about ZJ-platform Cherokees in general, along with claimed ample seat time in the 5.9 vehicles. This is worth noting as he cites self-measured performance results that may indicate this 5.9 has what’s known as the “Police” setting activated, a setting within the Powertrain Control Module that is activated via a special tool, and resulting in some combination of more aggressive shift settings and “…additional spark advance.”

The proof of this setting is hazy at best, but the seller cites magazine test data of one such 5.9 that had the setting activated that matches the performance of his truck. Most notably, the run to 60 m.p.h. is recorded as being under seven seconds, while on non-Police setting 5.9s the same run takes 7.3 seconds. The seller also feels his truck has the firmer shift patterns said to be part of the Police setting activation. On another note, the condition of the Grand Cherokee appears excellent in photos, with a nicely preserved interior despite 210,000 miles.

The listing goes on to provide an extremely detailed assessment of the Jeep’s condition, the highlight of which is the claimed rust-free body and frame. The seller notes the engine and transmission function as intended, but that there is a pending automatic transmission service for the next owner to tackle. In addition, the viscous coupling is binding at low speeds, and the seller further adds that several of the suspension bushings are worn and due for replacement. Given the healthy amount of data in the listing, this seems like the type of seller you want to buy from;  if the Police settings can be verified, that adds to this particular 5.9’s appeal as well.

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  1. Robert knight

    I have one just like it. Great vehicle other than poor on mileage and front end issues.

    Like 7
  2. CanuckCarGuy

    The agility of drunken llama with gobs of power under the hood, what could possibly go wrong?

    Like 15
  3. Superdessucke

    I always thought these big performance SUVs made about as much sense as a Chrysler Imperial Super Bee with a 440 Six Pack, but whatever, they are reality now. This was one of the forefathers.

    Like 2
  4. Dave

    I know of several instances of the “police” Cherokee/GC being used as police vehicles, circa 1998-2005.

    The MA State Police had quite a few of them, unmarked, used by detectives assigned to the GHQ Crime Lab. I think they all saw the auction block by 2006. They weren’t well-loved by Fleet and I believe only one order/contract was ever completed. Title and registration on those appeared as normal with no special order code or phrasing. The interiors were simple with cloth seats. There were some additional mods done as deemed necessary, including to the interior.

    The town of Webster, MA, PD had at least one as a marked patrol vehicle. It was handed down to the PD auxiliary before being deemed unserviceable. A friend of mine was one of the last officers to operate it before he retired.

    The town of Hinesburg, VT, also had at least one as a marked unit, as recently as 2007. I saw it on the road but have never worked for that agency so I don’t know the details.

    Like 10
  5. rick

    I had one of these for a couple of years, what a rush! Truely a muscle car SUV. Premium gas only, would go anywhere you wanted. Switched to a Yukon for better towing capability. Missed the Jeep though so I got a 98 5.3 ZJ for winter.

    Like 3
  6. Glo

    That’s exactly what I have bought it 450 as is and put about 3000 into it but now it needs a blower LoL 😂.

    Like 0
  7. Michael L Runnels

    Love mine as well. white w/ blk interior and only 58k. she’s never seen snow or slated roads and only an occasional rain shower. stays in controlled garage under indoor cover, but does come out on nice days..:)

    Like 0
  8. sdallas

    I have owned 2 of these and I can tell you with near certainty that there is no “police mode”. The PCM of these vehicles come factory equipped with advanced timing and other settings that cause it to require 93 octane gas. If you use less than 93 you get pre-detonation. After buying these Jeeps and realizing the HORRIBLE mileage and cost of premium gas people began to complain to Chrysler. Chrysler came up with a DETUNING program so that the ZJ could run on regular unleaded gas i.e. 87 octane. I have owned one de-tuned 5.9 and one that was not de-tuned. You can go to Chrysler have which ever tune you wish put on the vehicle but there is no police mode that does anything to the engine. The extreme close up of the DRB II scanner only makes me more suspicious. I have a cousin who works at a Chrysler dealership and there are in fact only 2 tunes for a 1998 ZJ 5.9. All that being said there very well be a dealership that has a custom made program for police models that does SOMETHING. That something however is likely NOT a performance gain of .5 seconds. Horsepower in that model is very limited by the intake manifold, exhaust manifold, cylinder heads etc. to meet emission standards. To gain .5 seconds you need better airflow by replacing or modifying those parts. A tune isn’t going to do it. There are also aftermarket tuners that may be beneficial but again…any significant gains in this vehicle will require replacement of parts. This Jeep is not worth what he is asking. They are a niche vehicle that have typical Jeep problems, horrible gas mileage and a crappy transfer case and haven’t reached the collectible level……YET.

    Like 2
  9. Gay Car Nut

    I’ve always loved this generation Jeep Grand Cherokee. I’d purchase one if I hadn’t already bought one a year ago. Lovely looking Jeep.

    Like 3
  10. RacerFX

    I had a 1995 V8… one of my favorites until the gremlins got to her. With a good set of tires, the Grand Cherokee handled fairly well. Always wanted to take it off road in Montana but never had the chance. Would love to have this vehicle off the showroom floor. 210k are a lot of miles. Would rather find a low mile version and flip out the engine for less money.

    Like 0
  11. Durkee Thompson


    Like 0
    • Rick

      Rockauto.com four seasons 35879 is the part number. Its a complete kit.

      Like 0
  12. Fiete T.

    “Police” setting?
    Is it right next to the “Turbo” button?
    I believe that like “It’s chipped.” Yeah, maybe if it was 1987 when Mopar Performance sold a re-chip. See, these are programmable- why have the expense of producing ECU’s with buttons? Quick reflash at the dealer before delivery

    Like 1
  13. GTiDave

    I’d like to see a pic of the slot you put a tool in, a re-flash is more like it for a 98 ECU. I worked on the ZJ program for the re-style (brake systems) and don’t remember hearing about a “setting”. Fun fact, the platform was supposed to have independent front/rear suspension but they didn’t like the cost, so it went away along with the turbo button..

    Like 1

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