Odometer quit - Help

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Our 1998. 5 QC 4x4 has 102,000 mi. on it and has just lost its odometer. The digital display quit. I took it to the dealer because I don't know anything about electronics and I thought it was computer controlled. All I really got out of the trip to the dealer is that the display is good, the sending unit on the pumpkin is good ("they think")and all that can be done about it is to get a new instrument cluster from Chrysler (aaagh those are expensive and cost a lot of down time). My question is can anyone out there point me in the right direction so I can fix this thing on my own (It sounds to me like a wire? Has anyone had this problem?

 

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Ghostroller- it is more likely a bad solder joint on the PC board for the odometer display itself, or a bad connection in the dash cluster itself, because that part is self-contained. My best advice is, before you bite the whole cluster bullet, take the dash cluster out, and if you can get near the area where the odometer is, wiggle everything, check for tiny cracks around any PC board solder joints (resolder as needed), and put it back in hoping hoping for a display to show back up. Since it is all gone, it is most likely no power, no ground or no signal, and all of that happens in the cluster. Good Luck! J.

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'01 Patriot Blue over Driftwood 2500 4x4 QC, snow plow prep, auto, 4. 10 LS, camper pack, tow mirrors (gotta love these!), American Racing Silver Atlas mags, Q-Logic 12" Cabinet w/Kicker amp , Mopar 12-CD changer, Sport lighting w. Brite Box, Stainless Luverne Boards, factory flairs, Line-X, and yet to re-install... . Janetty 4" exhaust, U. S. Gear 4" decellerator, K&N, cup-smoothie ;-) and a bunch of other BOMB-lite stuff like guages ... ...

 

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Ghostrolller,

NTENNA gave you good advice, I'd just add a couple of things... . as you are taking it apart, make sure you know where EVERY screw and spacer came from. Lay out the screws on a large piece of paper with a crude drawing of the cluster. That way you will at least have a clue as to where the parts go when you are done.
When you start inspecting the connections, use a high intensity lamp and a magnifying lens of some kind, those breaks can be awfully small.
Keep the soldering iron at a reasonable heat. You should NOT need anything over about a 25 Watt iron to resolder the bad connection. Some . 032 ROSIN core 60/40 solder will come in handy. Any Radio Shack will have it.
A bad connection will look whitish or grey. The good connections will be bright and shiny. Sometimes you will be able to wiggle the component (carefully) and feel the lead on the other side move ever so slightly.
Printed circuit boards are NOT magic but very hard to diagnose at times.


Mick2500


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2001 2500 ETH/DEE, QuadCab, 4X4, SB, LSD, 3. 54, SLT+, Sport, Intense Blue PC/Agate, Tow Package, Camper Package, 'DC' Bed Cover, Sliding rear window. Ordered 5/01/00... Cancelled 5/30/00... re-ordered 6/02/00... Cancelled again by DC 6/05/00
Gauges (EGT/Boost) and A-Pillar mount Here, 4" Exhaust, Here.
UPDATE!! Re-ordered 7/7/00..... Finally a new VON,
Status BX 7/11/00,
Status D 7/12/00 (I now have a VIN)!!

 

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I think your problem is in the wiring between the sender and the dash. Check for lose or corroded connectors,some may be hard to get at. Sometimes mice will chew on wiring and even though they don't go all the way through it sets the stage for corrosion which can short out a wire. You can also use a ohm meter to check for open wires,easy way is to disconnect both wires at both ends,short one pair together then measure the resistence at the other end. Don't let anyone talk you into a new inst. cluster,I doubt that is the problem.

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95' 25004X4,AT,Driftwood,Banks,Warn fender flairs and running boards(Play truck)95 3500,5 speed,driftwood,Banks&phscotty,30,000 GVW apple and tractor hauler(work truck)

 

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Originally posted by illflem:
I think your problem is in the wiring between the sender and the dash. ... Don't let anyone talk you into a new inst. cluster,I doubt that is the problem.

I don't have Dave Fritz's URL handy. I *thought* I saw a TSB about failing instrument clusters not long ago. But I'm not certain of that.

The way the system works on the 98, which *should be the way it works on the 98. 5:
The rear wheel sensor sends a signal to the CAB (antilick brake controller). It sends a signal to the PCM. The PCM interprets this signal and sends a message over the CCD bus to the instrument cluster, which then displays the desired data.

If the instrument cluster fails to receive the requisite messaging from the PCM, it displays the last received mileage reading. If the instrument cluster has received no messages since the current key-on cycle, the odometer will blink.

So, if your odometer is not displaying at all, then it is likely an electrical problem. If nothing on the cluster works, it is more likely a cluster power problem. If only the odo doesn't work, I might suspect an electrical connection in its general vicinity (likely on the PCB).

If you are paying someone else to check it out, it'll likely be cheaper to buy a new cluster. If you can peruse the electrical stuff yourself (and you have the time), check it out yourself; you might be able to fix it.

Fest3er

 

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The odometer that failed the other day began working again for a short time and now blinks like you described and does not register new mileage accrued when driving. We pulled the dash apart and found a harness going to the instrument cluster that has been abraided by one of the bolts in the steel work under the dash. Before we cut the external wrap off the wiring harness does any one know if a wire transfers mileage information to the odometer and what color it is? Also this truck is scheduled to head for the east coast Monday and won't be back for a month; do any of the on board computers store the mileage reading and can this information be retrieved to correct our nonfunctional odometer?

 

[Archive]

Originally posted by Ghostroller:
... Before we cut the external wrap off the wiring harness does any one know if a wire transfers mileage information to the odometer and what color it is? ... do any of the on board computers store the mileage reading and can this information be retrieved to correct our nonfunctional odometer?

The PCM stores the actual total mileage and the trip mileage. Upon key-on, it transfers this info to the instrument cluster via the CCD bus. Once the cluster is talking to the PCM again, it will display the correct data.

The CCD+ and CCD- wires from the inst. clust. are
VT/BR and WT/BK, respectively, to 'joint connector #7'. Between there and the PCM, they are VT/BR and WT/BR, changing to VT/BK and WT/BK, respectively.
(CCD: Chrysler Collision Detection; a data bus used to transfer information around the vehicle. )

If the CCD bus was disrupted before the inst. clust. , I would expect it to work erratically. I. e. , the speedo would be jumpy, the tach should be jumpy, other gauges would be similarly flakey. If all the other gauges have been stable, and *only* the odo was failing, I would tend to suspect wiring/traces internal to the instrument cluster.

As to the mileage, the PCM stores it, regardless of
whether the inst. clust. displays it. When you get the display working again, the correct mileage will show up.

This is all according to the SM. And they've been known to have misprints. And errors. But this is generally how the system works.

Fest3er

 

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I did notice that if the batteries are disconnected that the Trip OD would reset to zero but total mileage was just fine. So another question is - Does the PCM have a EEProm that stores mileage? or does it have a battery backup?

 

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Originally posted by BV:
... So another question is - Does the PCM have a EEProm that stores mileage? or does it have a battery backup?

EEPROM, NVRAM, Flash RAM; any of these would accomplish the task of persistent memory. It would have to be something like this; battery backup wouldn't guarantee that the total miles remains stored, whereas non-volatile memory is harder to erase.