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VP 2002B Deluxe Panel Temp Gauge

kerrydeare

New member
My 2002 (1993) has 3700 hours and runs well. The deluxe panel also was fine with all gauges except the tach performing properly. I have replaced the original tach with the latest (both wires removed from the old sender and one of these to "w" on the alternator, the hour meter wire removed and set aside, etc.). I just started up the engine for the upcoming season and the new tach is fine. However now I have a new issue with the temp gauge. Here are the symptoms.

Prior to starting, when I turn the key one click, all gauges including the temp move a bit, indicating that the wiring is fine to all instruments. Nothing happens with the tach of course. When I then start up, all gauges including the new tach perform as designed, except that the old temp gauge (which ran perfectly last year) pegs to the left once the engine starts, giving what looks like reverse polarity connection symptoms. I did not change any wiring to this gauge when fiting the new tach.

Next, when I shut down after running the engine under load and letting it come to temp, all the gauges including the temp show what appear to be correct readings, but only when the engine is NOT actually running. That is, it seems the temp sender is OK and sending correct info, the oil sender same, the voltage meter same, the tack off of course, etc. I think this means the temp sender is fine, but that running the engine is somehow sending the incorrect voltage to the meter. Only when I start up and the engine is actually running (and the tach showing the revs) does the temp gauge peg to the left. Is it possible I just picked the wwrong one of the 2 old tach wires for the new tach to connect to "w"? No other wiring changed from the time the temp gauge was OK. Ideas welcomed.
 
Kerry,

I think you are right...it sounds like a reversed polarity problem. Did you, somehow swap the wiring? Any place that, maybe it does cross polarity?

Just my 2 cents worth,
BobT
 
...it sounds like a reversed polarity problem. Did you, somehow swap the wiring? ...
Yesterday I tried to switch the wires running from the original tach to the tach sender. In the new setup one of these is connected to "w" on the alternator. It happens that they actually are terminated with different size connectors and only one of these will fit the new lug that is packaged with the new tach. So I guess Volvo is telling me they ARE different and only fit in one way. So much for my polarity idea.
 
Kerry,

Maybe not, is your temp tranducer one wire or two? Temp Gage? Might try reversing those...it does sound like a reversed polarity. I went thru a simular problem swapping out my complete instrument pannels, (4ea). Had TAMD40As and installed TAMD41As, but kept the 40A's instrument pannels. Had to use the old 40A's oil pressure sending units with the new tachs. Don't know why, just didn't work with the newer engines.

Hope you find the cause, let us know...
BobT
 
... is your temp tranducer one wire or two? Temp Gage? Might try reversing those...it does sound like a reversed polarity ...
Hope you find the cause, let us know...
I think we're getting warm. Yesterday I tried various combinations, including just disconnecting the wire to the "w" lug. I had assumed that this wire, one of 2, belonged to the old tach. When I then tried the engine with this wire disconnected the tach still worked but the temp gauge was "dead."

In other words I suspect that my problem is that instead of disconnecting the wires I may have mistakenly assumed belonged to the old tach, I actually disconnected the wires from the temp sender, and then connected one of these to "w" on the alternator. This fits all the symptoms so far, and could easily have happened since I am not really sure which sender is temp and which is revs. My manual does not show the locations clearly. Another clue that the pair I dosconnected has 2 different sized lugs, fitting the description of the temp sender wires given to me by Richard Vosbury of Annapolis. I suspect the larger lug is the actual temp resistor and the smaller lug is the temp alarm.

Today I will run down to the boatyard and try again, this time using the correct pair of wires (assuming I can locate them somewhere in the vicinity of the alternator on the starboard side of the engine). In he meantime, any more comments on these suppositions? Putting all the comments together so far is at least giving this confused amateur some ideas on how to proceed. Thanks, gentlemen.
 
DN-RTFM Department

... I suspect that my problem is that ... I actually disconnected the wires from the temp sender, and then connected one of these to "w" on the alternator ...
The subject line says it all. DO NOT RTFM! Had I ignored the instructions packaged with the new tach and just switched it out, everything would have been OK from the beginning. The instructions evidently do not take into account that during the manufacturing run of this model quite a few changes were incorporated, including the latest wiring for the tach. Unfortunately no one in the marketing department was notified that changes in the brochures were in order. Today I just undid all the changes made according to the installation literature, essentially just dropped in the replacement tach, and all works per design.
 
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