[Sam-n-I]

Good Day, I have a 2002 38 open and my starboard gages (oil pressure, engine temp, transmission temp, etc.) all are erratic.  Sometimes 2 of them will work fine but normally they are erratic.  I feel it is a grounding problem.  Problem is I have not been able to find the ground wire/cable off the engine.  Does anyone have experience with this and do you know when to find the ground cable?  Thanks

[ReelMagic]

I own a 2003 38 Open and have the wiring diagrams from Tiara. Not sure if you do. If so I would start there. If you need diagrams I may be able to help. There are quite a few, 20 or so.... Let me know

[jclark003]

Is your engine electronic (3126B)? If so there is a 70 pin customer connector, rear of engine near air cleaner. Check the connection and if possible, clean the pins inside the connector. Battery negative should be on pins 2 and 3

[twilson0929]

Good Day, I have a 2002 38 open and my starboard gages (oil pressure, engine temp, transmission temp, etc.) all are erratic.  Sometimes 2 of them will work fine but normally they are erratic.  I feel it is a grounding problem.  Problem is I have not been able to find the ground wire/cable off the engine.  Does anyone have experience with this and do you know when to find the ground cable?  Thanks

I have a similar issue on 2001 3800 Open with Cummins 450’s that just started with my port engine alarm alerting at higher speeds or in choppy water. Gauges are now fluctuating.  Have you had any success finding the cause? I have local shop looking at this week. They just installed new Garmin electronics and the issue has gotten worse.  Will advise what they find.

[trit21]

My 2000 Tiara 3500 , Cummins 6BTA, has had issues with ground as you specify. Gauges would fluctuate or not work at all and occasionally I would have alarm go off that is located behind helm for oil pressure, temp, battery charge etc. My problem has ALWAYS been the ground wires behind the helm. Mostly the ones that are directly connected to the gauges as they are just piggy backed from one to the other and sometimes the spade connectors get loose causing poor grounding. If you are also have issue with a newly installed electronics package, I would suggest looking at the main ground block behind the helm. Mine has also loosened up causing erratic ground issue seen by poor voltage readings at helm gauges and gauges not working or erratic.

Hope this helps.

[twilson0929]

My 2000 Tiara 3500 , Cummins 6BTA, has had issues with ground as you specify. Gauges would fluctuate or not work at all and occasionally I would have alarm go off that is located behind helm for oil pressure, temp, battery charge etc. My problem has ALWAYS been the ground wires behind the helm. Mostly the ones that are directly connected to the gauges as they are just piggy backed from one to the other and sometimes the spade connectors get loose causing poor grounding. If you are also have issue with a newly installed electronics package, I would suggest looking at the main ground block behind the helm. Mine has also loosened up causing erratic ground issue seen by poor voltage readings at helm gauges and gauges not working or erratic.

Hope this helps.

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That’s helps. The main ground panel behind the helm seems ok. Took most off, cleaned, reattached but no change. The actual ground wires to the back of the gauges come off very easy. Coated with dielectric grease, seems to help some...but hasn’t fixed issue. I will have to pull each one. Not an easy place to hang out in and work on. Thanks for info.

[jclark003]

If your grounds all check out look at the +vdc leads coming from the key switch. A poor connection there or a bad switch can cause voltage fluxuations resulting in the same symptoms. One easy check is to start the engines and run a jumper across the key switch battery and run terminals (not the start terminal). Just be aware that engine will not stop as long as jumper is in place. Battery usually has a red wire attached and is always energized and run typically has purple wires attached and is only energized when the switch is in the run position.

[twilson0929]

I’m having the same issue on my 01 3800. Port tach works for 5 min after start then gets erratic. Starboard tach slightly more consistent. Alarm goes off in choppy water. I have used electric grease on most fittings I can reach that jump gauge to gauge. I will check the ground at the key this weekend. Ground bus was cleaned and greased no change. Not sure if there are any grounds to check on the engine synchronizer or not. If anyone has found the solution please share. Thx!

[sjcrum]

I had the same issue with my 2000 Tiara with Cummins 6BTA's. I replaced the master boards, all sensors, and everything on the tachs including rebuilding the tachs, same issue ( tachs jumps and false alarms). I finally inspected the wire connections on the coolant temperature sensors, and one had bare wires. I removed the spade connector, reconnected, and thus far, (knock on wood) the issue seems to have gone away. I did take it out in fall before pull out, got it up to temperature and in decent size waves, no tach jumping and no alarms.
Something to look at, I think the reason it mainly became erratic in bigger waves was the motion caused the bare wires to touch.