My '98 LS had a loose battery connection that caused the car to go dead after switching from ON to ACC. Weird. Anyway, in the repair there was the usual little spark at reconnect, and now the speedometer stops at 15mph rather than 0. It's not quite an offset either, as whatever went wrong has shifted the slope a bit, such that 75mph reads as 100.

So, two questions:

1) What's the fix here? The forum has been oddly vague. Batteries die every day, so this can't be that unique of an issue.
2) I stumbled into a cluster menu that reeks of a service function, but I can't get past the first level. Anyone know what's needed to operate it? I've not found this menu in AllData. To access it, I pressed the "Reset" button on the cluster with the key off, then keyed on, and held the button until the power on test completed. I then released, and the message screen went blank other than "Sp". Pushing the TRIP/ODO button toggles to "Ta", "Fu", or "Te". Holding TRIP/ODO for 5 seconds while on any of those options and then releasing it causes the number "0" to appear to the right. No combination or duration of cluster, steering wheel, or dash button pushes that I've tried (and I tried a lot) causes the cluster to respond or the "0" to change. I can't help but think I've hit a wall that needs a service handheld to get further, and that chews at my Right-to-Repair frustrations. Any ideas, @Yamae ?

 

I'd try resetting the system just removing the negative battery terminal for 1 hour+ and then reconnect it. The reason to wait 1 hour+ is to remove stray electrons in the chips. Sometimes longer than a half day is needed depending on situations though.

 

I forgot to add that I pulled the terminal before dinner yesterday and reinstalled before leaving for work this morning - a solid 10+ hours of open circuit time. The needle went right back to 15 after the terminal was reinstalled.

 

These are the only pages I could find in my '98 service manual regarding the combination meter. I don't know how helpful they'd be (I just did a quick skim) but I'll attach them anyway.

I couldn't find anything in the Diagnostics section of the manual.

 

Many thanks. I'll give 'em a look. If it's capacitors, those little widgets seem to be the Achilles heel of these otherwise durable machines.

 

The solution is that the MPH motor assembly needs to be replaced. We repair multiple 98-00 clusters per week with similar gauge issues.

 

When was it started?

 

I drive it daily. I was having no issue, then the battery connection failed (thus the failed battery example). The speedometer developed this problem following the re-connection.

 

Other than the speedometer problem, the battery draining issue is there. I'd check the draining current first and find out the root cause of it. I imagine it is related to the speedometer problem.

 

I may have mis-described what's happening, @Yamae. I'm not having a battery drain problem. A previous owner had installed a poor quality battery terminal that failed allowing the cable to have an intermittent connection, occasionally causing a dead-vehicle condition, and at some point that poor connection caused my speedometer to go wrong. There have been no further electrical issues since the repair, but the speedometer is still resting at 15mph. Unless other ideas pop up as to how this could be remedied, I guess I'll be hitting the yards looking for a cluster, or digi-key for some caps.

Does no one have any direction on that menu I was able to access? That one is really interesting to me.

 

Now I understand that there was an intermittent connection time to time. In that case, I worry that the repetition of the connection and re-connection caused the surge pulse to the +B line and that might stress the electronics circuits. If so, it will not be easy to fix the problem. An electronically skilled guy would analyze the circuit and find out what is damaged but the quickest way to fix would be to replace the cluster unit finding a good used one.

Celsior's/LS400's all the electronics related circuits are designed to endure the surge energy of a certain level. But the repetition of the surge energy to the circuit sometimes damages the surge protector as is written in the link and the circuit is not fully protected.