D~C

Ok, so yesterday evening I started up my Jeep and got about a block away when I noticed the speedometer needle was bouncing all over the place. It did this for about 5 minutes before it dropped to zero MPH and just stayed there.

A short time later that evening, the Check Engine light came on. The OBD2 code reads P0500, which translates to Vehicle Speed Sensor "A" according to this Android app I'm using.

I went to my nearest Auto Zone and the guy there told me he believed the problem is that the speedo cable has frayed and broke. He said I should change the cable inside the housing, that connects from the back of the speedo to the tranny. So I bought a $4 replacement speedo cable.

I figured I'd come here for a second opinion(s), especially after reading a lot of conflicting approaches online. I've never messed with a speedo sensor/cable before. I'm not really a mechanic, but I have some tools and tinker every now and again.

Appreciate any help with this. In the meantime, I'll be using a speedo app on my phone to figure out how fast I'm driving.

CCKen

As usual, the Idiotzone counter pukes are full of it. The 1999 XJ speedometer is electronic. There is no 'cable'.

Either the Vehicle Speed Sensor (VSS) on the transmission is defective, the VSS wiring or connector is defective/corroded, or the plastic drive spline on the transmission output shaft is sheared/broken.

You can do a visual inspction of the wiring and connector, and remove the VSS and look inside the mounting hole in the trans at the VSS plastic drive. See if it's split or otherwise damaged. Look at the gear on the VSS and see if the splines on the drive gear are damaged.

If everything is in order a new VSS may be required.

Tell us what you find.

CCKen

Climb under the left side of your Jeep and look at the rear of the trans. This is what you should see. The black device is the VSS and its adaptor.

If you plan on removing the VSS, place a reference mark on the side of the VSS where it touches the trans and one on the trans. Match up the reference marks when reinstalling the VSS.

D~C

@ccken Ahhh. An electronic sensor. That's what I originally suspected! That Auto Zone dude was trying to convince me otherwise And now I can see why my research was so conflicting.

I'm going to crawl under there soon and see what is up.

Much obliged! I'll report back...

D~C

I went underneath and I saw essentially what was pictured above.

My quick visual didn't spot any apparent issues; everything looked intact. Re-seating/cleaning the connection did not help.

I'm thinking I'm going to just replace the VSS and see what happens.

I've been trying to track down a replacement VSS, which is proving to be dicey as I'm once again getting conflicting info from different sources.

Autozone (and a "mom n' pop" auto parts store here in town) tells me that there are two VSS versions; one for a 3-speed tranny ($30) and one for a 4-speed tranny ($135). I happen to have an A340F tranny in my 2WD 6-cyl 4.0L Cherokee that is a 4-speed automatic, so I can only assume that I need the more expensive VSS.

However, Napa tells me that there is only one version of the VSS that is $50.

My regular mechanic is telling me that his research is telling him that the VSS I need is a dealer-only item, but he knows a shop that might have a good used one. And that I should take a picture of my current one to as an aid to match it correctly. Otherwise, I'm looking at a $100+ part from a dealer.

Thoughts?

CCKen

The A340F is a brother to the AW4 but with some differences.

how do you know you have an A340F trans in your XJ?

Don't run out and buy a VSS until you remove the one you have and look inside its mount hole in the trans to see if the drive on the trans output shaft is damaged, and the drive gear on the VSS is damaged.

Can you take a pic of your VSS and post it here?

The VSS is a two part device. The speed sensor portion of the VSS mounts on an adaptor, and together they are referred to as the VSS. What you'll buy is the sensor portion. I haven't seen aftermarket adaptors.

CCKen

This is what the VSS assembly break-down looks like.

D~C

Thanks for the diagram!

I'll climb under and take those pics soon...

I was informed that I have an A340F tranny when it was pulled for a rebuild last December.

CCKen

Who ever told you that may have been going by the "30-40LE" on the data plate and cross referenced it to an A340F.

See what is on your data plate. It's on the right/lower side of the transmission, above the oil pan.

Edit: You should see the AW Model number 30-43LE, and Chrysler part number 52104180AC on the data plate.

D~C

Sorry for the delay in replying. I've barely had any time to focus on this project, and still have not had the opportunity to pull apart the VSS for inspection, etc..

However, I did just crawl under the vehicle looking for the tranny's data plate. I looked and looked, but could not find it. If you could provide a sample picture and/or further description, I'd be much obliged. And please specify driver's side/passenger side orientation language. Just FYI - the person who told me I have an A340F tranny is the person who rebuilt my tranny and runs the tranny shop.

CCKen

It is very hard to get a good look at it. A flashlight and mirror will help.

D~C

Thanks for that!

I didn't see it until just now, but I did pull the VSS for a quick inspection yesterday evening. I took a socket wrench to one bolt and a bit of tranny fluid poured out. It looked like the VSS has a green gear attached to the adapter end that was inside the tranny; there were some teeth chewed up a bit - guessing that's the root of my malfunctioning speedometer.

On a side note, I was at an auto parts store yesterday and they were telling me that if I have an A340F tranny then it's a 4-speed automatic requiring a VSS that has a magnet and costs $140.

I don't have the Jeep with me now, so I can't look again for the data plate.

CCKen

.

CCKen

Here's a page from the '99 parts catalog that shows the VSS Drive Gear inside the trans that I mentioned above. Look at item 19 - that's it.

The parts store ***** that talked about a $140 magnet gizmo is referring to the transmission output sensor. Item 16 is what triggers the output speed sensor. You don't need this.

D~C

Got it all squared away - thanks!!