OBD Reader on Comanches

[gogmorgo]

Just to clarify for anyone wondering about the emissions timer and "maint req'd" light. It's called a timer because that's what it is. It turns the light on after the odometer rolls past 80,000 miles. It has zero connection at all to anything other than the speedometer. Unless you have another reason to replace the O2 sensor, I wouldn't bother.

My bulb is burnt out or I pulled it once when I had the cluster out and forgot. Either way its not worth my time and effort to investigate.

[Eagle]

It doesn't have any connection to the speedometer, either. It can't -- the speedometers on the Renix MJs are mechanical, driven by a cable. It is literally a timer. It starts running when the ignition is turned on, and it stops when the ignition is turned off. It doesn't count to exactly 80,000 miles -- the factory made a bunch of assumptions about probable average usage, and built the timer to count down to when an average owner would hit 80,000 (or so) miles based on engine run hours.

[omega_rugal]

in other words, its a piece of $#!&, another big WHY? from AMC..

[Minuit]

On the '91 and '92 MJs the light is controlled by the computer. On the Renix MJs it's a "dumb" timer. It just counts like Eagle said. The 91 and 92s can have the light reset with the proper scan tool (MT2500, DRB-II, etc) but most people just pull the bulb and forget about it. 

 

It's just the early incarnation of maintenance minders you see on newer cars. It hasn't gone away.

[Jeep Driver]

in other words, its a piece of $#!&, another big WHY? from AMC..

Read up on some of the history of AMC. 

 

AMC's practices were the most innovative since Ford's production line. 

 

AMC invented 'outsourcing'. Now, every automaker outsources. 

 

 

 

TImer? and POS? yes. Driven by EPA, not AMC. Much of what took place in the 70s and 80s as it relates to 'safety' and emissions was driven by NHTSA and EPA, both of which have killed more people than they saved. 

[Green Mesa XJ]

It doesn't have any connection to the speedometer, either. It can't -- the speedometers on the Renix MJs are mechanical, driven by a cable. It is literally a timer. It starts running when the ignition is turned on, and it stops when the ignition is turned off. It doesn't count to exactly 80,000 miles -- the factory made a bunch of assumptions about probable average usage, and built the timer to count down to when an average owner would hit 80,000 (or so) miles based on engine run hours.

Found the timer box in a 1986 XJ 2.8 engine harness I put in my old XJ, the old harness didn't have a "timer" so I thought it was strange. Four wires running to a circuit is all it is, no idea why the 2.8 has a timer because as far as I can tell the 84-86 carbureted federal emission XJ/MJ do not have oxygen sensors . The California emissions 2.8 XJ have a crude computer and oxygen sensors.

 

Found photos of that timer from when I swapped the harness.

 

 

For what it's worth I had a old VW built right in the beginning of all these federal emissions regulations that had a mileage timer placed in the speedometer line between the cluster and the firewall (also didn't have oxygen sensors since it had no computer, mechanical fuel injection). The counter was on the outside of the firewall and VW made a small speedometer cable from the cluster to the box. Thing is this system sucked, the freaky little counter box broke and the speedometer in the car never read accurately again. No replacement parts cause it was one year only. Only a few VWs imported and converted to met federal regulations had this counter, most I found in junk yards were already broken.

For all of AMC & jeeps short coming they were always easier to source parts for than that VW .

 

 

 

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[Green Mesa XJ]

The Innova 3140 scan tool kit can read OBD I jeeps, comes with an adapter to fit the computer plug in the engine bay. However the 1991 HO light to check the O2 sensor can not be reset by this scan tool. Had to be a Chrysler tool to reset that specific light. Supposedly 92 and later can be reset by hand scanners but no idea if that's true.

 

 

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[HOrnbrod]

The Innova 3140 scan tool kit can read OBD I jeeps, comes with an adapter to fit the computer plug in the engine bay. However the 1991 HO light to check the O2 sensor can not be reset by this scan tool. Had to be a Chrysler tool to reset that specific light. Supposedly 92 and later can be reset by hand scanners but no idea if that's true.

 

 

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The Actron 9145 AutoScanner can read Jeep Chrysler ODD1 codes as well. 

 

http://comancheclub.com/topic/46667-actron-obd1-scanner/?hl=actron

[omega_rugal]

Read up on some of the history of AMC. 

 

AMC's practices were the most innovative since Ford's production line. 

 

AMC invented 'outsourcing'. Now, every automaker outsources. 

 

 

TImer? and POS? yes. Driven by EPA, not AMC. Much of what took place in the 70s and 80s as it relates to 'safety' and emissions was driven by NHTSA and EPA, both of which have killed more people than they saved. 

 

 

what i meant is they could implement something better than basicly an alarm clock and a message tha would say "Change O2 sensor you dumb@#$%" instead of "Emission maintence"