Whats runs the RPM lights on the stock dash cluster?

[jdpolzin]

I'm working on a buddies car and his RPM lights on the dash cluster are always completely lit up. I'm wondering if its something in the cluster thats screwed up or if it the crank sensor thats bad? Does the crank sensor send the signal for these lights? The car runs fine so the crank sensor must be doing it's job but the light are all on constantly. What do you guys think may be the problem?

 

[Drewster]

There are 2 connectors behind the alternator (toward dipstick). people have a habit of connecting them be cause they fit. These should not be connected because one is for the fuel pump (alternate power feed) and one is for the tach (diagnosic testing).

if these are connected, pull them apart and see if it fixes it.

Andrew

 

[davelostmissing]

oops

 

[davelostmissing]

again

 

[bmackinnon]

What do you guys think may be the problem?

This is a chronic problem with our cars and is explained in detail by John Spina, owner of Casper's Electronics... involves time related degradation of the tach/boost led circuitry..... read all about it here:

http://www.installationinstructions.com/FYI/tachboost.pdf

If you want it to work correctly again, John offers a repair/recalibration service... $92.50..... here:

CEI - Casper's Electronics, Inc.

That should about cover it??? :tongue:

 

[mikestertwo]

Sounds like your digital tach died. Send it to John, I think he still repairs them. If you had the fuel pump lead tied to the tach lead behind the alternator the tach would read "0" all the time.

 

[jdpolzin]

OK, I thought it may have something to do with the dash taking a dump but I wanted to make sure before I got to involved in it. It's not my car so I wont be spending any money on it. But if it was an easy fix, I would just fix it for Moooven6. No biggie.

 

[85HotAirGN]

I have the same problem, my tach reads 5 or 6 all the time and then with a little throttle stays maxed out.

I connected those wires and the tach just stayed at 1000RPM and didn't move at all, so I went back and disconnected them.

Glad this was posted, hopefully I can find the solution through the link that was posted.