BS: Mechanic Advice Needed/Jeep

Subject: BS: Mechanic Advice Needed/Jeep
From: Sorcha
Date: 20 Nov 04 - 12:11 PM

Help! I know Mr is a mechanic, but this one has him stumped. The speedometer on my 96 Jeep Grand Cherokee is not working right. Sometimes it doesn't work at all, other times fine, others intermittently, and sometimes goes plumb crazy. We've changed the sensing/sending module and it didn't help....damn thing is electronic. Any bright Ideas? Thanks!

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: catspaw49
Date: 20 Nov 04 - 12:21 PM

Strikes me that the cruise control is also involved even electroniaclly.......

Spaw

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Sorcha
Date: 20 Nov 04 - 12:25 PM

I was hoping you'd see this.....we've tried both with cruise on and off...no joy. Now what??

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Amos
Date: 20 Nov 04 - 12:31 PM

You could be looking at an intermittent short of some kind, possibly moisture-related or through some cable degradation if there is wiring. Loose connectors or plugs can also cause intermittent hay-wire reads on electronic units. If there's a chip involved in doing the electronic interpretation, that could be the bugger, a component-replace solution.

A

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: GUEST
Date: 20 Nov 04 - 06:15 PM

Trade it in for a decent Toyota 4x4 or Landrover.....

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Sorcha
Date: 20 Nov 04 - 08:12 PM

That is fucking helpful...had one.....it died.

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Bobert
Date: 20 Nov 04 - 08:23 PM

Does the odometer work when the speedometer is not working?

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Mark Cohen
Date: 21 Nov 04 - 04:11 AM

When I had my '93 Grand Cherokee Limited, living in a macadamia nut orchard on the Big Island, the cause for most any electrical problem generally turned out to be a mouse eating the wiring.

Aloha,
Mark

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: John MacKenzie
Date: 21 Nov 04 - 04:53 AM

I assume it's a 'fly by wire' speedo in which case it can only be electrical interferencefrom another bit of the engine management system, especially when you've replaced the sender. A big culprit for misbehaving electrics is a badly earthed engine so that's where I'd go next, if you've done that then try spraying WD40 or any water dispersant fluid on all the wiring you can find, as it may be power leakage somewhere else emitting a frequency wave that interferes with the sender for your speedo. I'm no expert on modern car electronics, and find they get more and more complicated as I get older, and less able to learn new tricks.
Giok
[check all fuses]

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Sorcha
Date: 21 Nov 04 - 11:08 AM

Yes, odometer works fine. Thanks, keep em coming!

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Wilfried Schaum
Date: 22 Nov 04 - 05:42 AM

A Jeep with electronics? Degenerate. Mine was a Korea veteran, all devices mechanic except the starter. Even the wipers could be operated by hand.

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: Gervase
Date: 22 Nov 04 - 07:20 AM

Bloody electronics, they've got no place in a workhorse!
I had a similar problem with a Renault once, and it turned out to be a crack in the PCB behind the dash that held all the relays and clever gizmos. Engine vibration would sometimes cause the crack to open, shutting off everything that ran across where the crack was and making the dash flash and flicker like a Christmas Tree. Fixed it with some solder - but with modern cars that's probably far too crude.
(*sigh* that's why I love my leaky Land Rover!)

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: GUEST,Nick
Date: 05 Dec 04 - 03:39 PM

I have the same problem with my 1995 Grand Cherokee and I was told that the speedometer its self is bad.

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: catspaw49
Date: 05 Dec 04 - 04:12 PM

I think you're at the point of determining where the "brain" for the CC lies. Could be in the speed triggering device or within the ECM itself. Got a wiring diagram?

Spaw

Subject: RE: BS: Mechanic Advice Needed/Jeep
From: GUEST
Date: 06 Dec 04 - 01:49 PM

Asking for advice on this forum is really dumb. Go to a reliable garage and ask a mechanic to fix it Sorcha