Vdo gauges and Cummins 370 6bta

[Jason Fanghella]

Long time lurker and learner never posted anything yet but looking for some help. I have a 2002 topaz with twin 370 6bta Cummins and running VDO gauges. I’m trying to figure out why my port tach doesn’t work until around 2400 rpm but isn’t actually accurate and doesn’t show any higher no matter what rpm. While my starboard tach just started doing almost the complete opposite. Once I hit about 1600 rpm the starboard tach goes to zero and stays there.

I have tested the volts to the gauges, everything is 12 or above. Then I checked the ohms from the harness to the gauges and from what I think it was almost 0 less than .001, so I am thinking about buying a new instrument cluster (the six pack looking one) or going to the digital gauges by seaboard which look great.

I’m up for any ideas to tes further. I tried to get amps out of it while running but was unsuccessful. I will post pictures of them as soon as I can get back.

Here are the serial numbers
46076453
46076490

Thanks for everything.

Topic

[Jason Fanghella]

Hi tony I apologize for the bad picture of the solenoid. It actually turned out to not be the heater. After a long week of testing and running everything I think I have it narrowed down to the actual harness to the gauges and it looks like I will be getting a pair of your SMX analog to digital 6bta gauges. Looking forward to working with you and seeing how great these come out.

[Jason Fanghella]

Hi Tony, sorry for the bad picture. The liquid is actually PB blaster. I hit more then I wanted to. But will get better pictures soon. The solenoid looks to me like part of the air heater assembly. The first contractor is actually melted off. I looked at your schematic of the assembly and it looks like it tire into the tach somehow. I will get a better picture with all the PB blaster off. Thanks

[Tony Athens]

Curious——–Am I looking at a 12VDC electrically operated magnetic switch that is cover in water, like in “saltwater” ?

Can I see some pictures of the rest of your engine?

Tony

[Jason Fanghella]

Thanks Tony, so far u took off all grounds and cleaned and remounted. I did notice today there was a burnt solenoid seems like the air heater. Would that have any effect on the tach sensors? I found a schematic and it seems like they are all connected. I will send the only picture I could manage from today. Also I will be checking straight from the tach sensor to see what amps and voltage I get from them.

[Tony Athens]

Start with this:

https://www.sbmar.com/articles/install-magnetic-pickup-drive-tachometer/

Tony

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