Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: emboli on November 17, 2012, 03:23:23 PM

Title: Solenoid supply voltage
Post by: emboli on November 17, 2012, 03:23:23 PM: Hi,

I'm having some issues with my 2003 2.7 CRD Grand Cherokee. I've had an intermittent transmission fault for the past couple of months. But don't have a local shop that can read the TCM, so i've taken the plunge to try and fault find the issue (error codes P0700 & P0702).

I've swung a probe over the TCM plugs C1 & C2 - the solenoid supply voltage (C2 - 38) is reading 3.9V. It sounds a little low to me - any idea if this is correct.

Also - to test the resistance of the solenoids; any idea which pins - control to ground?

Thanks in advance.
Title: Re: Solenoid supply voltage
Post by: Lukemagnum on November 17, 2012, 04:34:41 PM: P0700 is a generic code for a transmission fault, you'll need decent scanner to pinpoint the exact fault.

Having said that, 9 times out of 10 it's a faulty speed sensor, either input or output. They're not that dear, on the Merc (same box) they're the same part, buy a new one for the front, if fault re-occurs swap out the back one.
Title: Re: Solenoid supply voltage
Post by: emboli on November 17, 2012, 04:43:46 PM: Thanks for the reply - do you know if there is anyway of testing the sensor - resistance, voltage or signal shape?
Title: Re: Solenoid supply voltage
Post by: Lukemagnum on November 17, 2012, 06:41:53 PM: I've only a basic understanding of electronics. It's likely to be a standard hall effect switch, so you'll need an oscilloscope to measure it.

Measuring resistance or using a normal meter will not tell you if it's triggering, so is meaningless.
Title: Re: Solenoid supply voltage
Post by: Dave The Sparky on November 17, 2012, 06:49:20 PM: If its a hall effect sensor then a multimeter with frequency setting will tell you what Hz the switch is kicking out so may point you in the right direction.
Title: Re: Solenoid supply voltage
Post by: emboli on November 21, 2012, 12:15:30 PM: Time to brush off the old scope then - may have found a local Merc Gearbox specialist that can do a DRBIII reading too.