Re: Re: Re: 95 3.9 no power

From: Tom (booyang1@hotmail.com)
Date: Wed Mar 24 2004 - 20:05:27 EST


Droo,

    The procedure is simple enough, but if you've never used a
multimeter before, I'd recommend you either have someone there to help
you or have a shop check it for you.

    Start your truck and let it warm up, and then run it above 1200rpm
for at least 2 minutes. Check the voltage between pin 41 on the PCM
connector and ground. The voltage should fluctuate between 400 and 600
milivolts (0.4 - 0.6 volts). If the voltage is not in that range, or if
the voltage stabilizes at either end, then the sensor is probably going bad.

    To check if the sensor is shorted to ground, do a resistance check
between pin 41 and ground. If the resistance is low (a few ohms or
less), then the sensor is probably shorted. If the resistance is
infinite (OL - "open line", or very large), then the sensor isn't grounded.

    It should take about 10 minutes to change out the sensor if it's
bad. On the Gen 1 Daks, it's in the exhaust pipe right at the Y-pipe
where the exhaust manifolds join together; you can see it looking down
the right (passenger's) side of the engine with the hood open.

    You don't have to remove the sensor to check it. Hope this helps.

             -Tom

droo wrote:
>
> On Tue, 23 Mar 2004 21:50:12 -0700, Tom <booyang1@hotmail.com> wrote:
>
>>
>> Not necessarily. The sensor is not grounded, it is simply
>> malfunctioning. It isn't doing anything that would cause a 21 (sensor
>> voltage shorted to ground, input voltage above normal range, neither
>> rich nor lean condition detected, or heating element malfunction).
>> The sensor seems to be constantly sending a lean condition signal (low
>> voltage, around 120mV) to the PCM, so all the PCM sees is a constant
>> lean condition and dumps fuel to richen the mixture.
>>
>>
>
> Luck that you boys are talking about o2 sensors. The engine light came
> on today in my truck. code p0131, o2 sensor shorting to ground. I got
> this before maybe a month and a half ago. It eventually went away and i
> figured the wet weather had something to do with it. Anyhow, it's back.
> I would like to know how to trouble shoot this before I take it to the
> dealer so I can at least tell them I found something wrong with it in
> case it goes back to normal. I've never used a volt meter before. I also
> don't know where to find it under the hood. I think the one on the
> exhaust is right after the cat. So when I'm testing, do I unplug the
> wire from the sensor or is there a way to do it while its plugged in?
> Also, what am I looking for?
>
>



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