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Junior Member
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Discussion Starter · #1 ·
Have a 12 valve with the automatic ,four speed with OD [37 RH] in a '93 D 250 . Where have people been mounting a sender for trans temperature guage? On tach installations with the Nippondenso alternator , i'm not seeing any tach relay provision, so what's been used over the years ? Can a lockup converter be installed on this trans, and what supplemental controls does it take to complete the job ?
 

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T.D.G. Mafia Member #88
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578 Posts
1st> The trans is a 46RH/A518 Non Lockup (factory)
2nd> Most guys "T" into the trans cooler line where the OD sensor threads in. I do not know the thread size on that though.
3rd>If your truck is a factory cummins in 93 then you should have tack provisions and here's a write up on it,http://www.dieseltruckresource.com/dev/showthread.php?t=173561 If not I'll try to find the alternator tear down to hardwire a tach signal.
4th>The 47RH from a 94-95 cummins can be found and used with a toggle to opperate lock up. The cost of obtaining lock up in your trans is possible I believe but most have swapped transmissions. This requires, engine adapter through transmission and even the starter from the same truck. This would give you your lock up. I personally recommend just a tighter converter for a DD. But if it's race apps then the lock up is money well spent.
 

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Premium Member
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2,641 Posts
There is a tach wire that comes from the PCM...

Looking at my books here the wire coming from the PCM is out of pin 29 wire color is Grey / Light Blue...:sly:

My buddies truck which is a 92 Cummins he's got a HALL effect tach in his truck...

I know Stewart Warner has diesel tach gauges that work on HALL effect sensors...
 

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Junior Member
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183 Posts
Discussion Starter · #4 ·
Thanks to Cummins pride and Mopar Man ! When I first referenced the Trans model, I did a quick look in my '92 manual that I got in Hershey last fall . 46RH is correct model,and reviewing the manual I see the statement that 46RH models are equipped with either a lockup or nonlockup converter .
And the reference to dieseltruckresource for the tach hookup pictures and
wiring schematic is so well detailed ! I have a tach that was used on a Delco 10SI with an added tach relay pin ,so hope it's compatible.Where's the mechanical drive provision for the "Hall Effect" sender[mechanical drive] on the engine ?
 

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Sorry I don't have a pic ready right now...

But the Hall effect is basically a magnetic pickup that is mount down near the crank damper. On my buddies 92 he's got a notch in the damper that the hall effect picks up as 1 revolution...

But I'd research the tach lead from the PCM... This should open more doors for available tach's...
 

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Senior Member
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I missed this post. I don't come into the section very much.

Your 93 has a factory tach harness on it. It is located to the left side of the steering column. It is a small flat 4 wire black plug.

Now for the bad news. The signal the PCM sends to the tach is only a 5 volt signal. Most auto tach can't read that low of voltage signal. Isspro and westach make tach's that do read the Dodge signal.

There is another company called tiny tach that take a reading from the #1 injection line. It reads the injection pulse from a line mounted pickup.

The 3rd option is using a Dakota Digital tach sending unit. It is supposed to read down to a 1 volt input signal. Then use any tach you like the looks of.

The last choise is the AutoMeter 2888 model it reads off the alt.
 

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After loosening everything up, one of Von Flue’s last steps before removal was removing the factory transmission pan and draining all its fluid.
 
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