Evil Ram

i'm trying to install my new tach autometer part #2890 low rev tach. Its got a red, green, black and white wires. I looked in the sticky and i found a pic of the factory tach plug that has 2wires, I checked everywere in my dash and around the steering column and could not find it am i doing something wrong here or does my truck even have that plug. All i could find is a 3wire plug red, brown and black. Red is power orange is power only when parking lights are on (guessing tach light) and black is ground, this plug is really short and rite on the column but could not get the tach to work What am i missing

Free89W350

I don't think the tachs were available until 92 but I could be wrong. Check your front cover and see if there is a crank position sensor on it. I believe the factory tachs ran off of the crank sensors. Otherwise you will have to make up a position sensor or run it off of the alternator.

freight train

The factory tach has 4 wires that run it! Your 91 will only have this plug if its intercooled (crankn sensor)! If equipped look for a inline black connector taped to the steering column under the dash! I have installed the factory tach 3 times and everytime it was there! Its not really electrical tape but more of a paper tape. But it is black in color! Its the only open plug there! Just incase you are wondering the little plug that connects the tach to the plug under the dash is (was) still available threw Dodge! It would make it alot easier to instal if you have it! I bought a tach from a dealer in Mizzu that just had the tach laying on the shelf. So I had to find 2 nuts, I used 2 washers instead of the underdash plate, and with the help of the new one I bought before I still had the empty individual bags that all the stuff came in I called my dealer and sure enough it was still available. Now that was about 2 or 3 yrs ago. Good luck!

peobryant

The '91 year trucks didn't have a crank position sensor, intercooled or not.

freight train

I thought mid to late 91's used an ECU to control the alternator and ac! I have never seen an intercooled truck with a voltage regulator on the firewall! Have you? But I have seen a 1991 with intercooler and ecu! To run the ecu it would have to have a crank sensor!

Ok, I was just looking over some pics! You are right! I just found a pic of a 1991 ,intercooled, with a voltage regulator on the firewall! My apologies!

wannadiesel

Easiest thing to do is send it back and get a #2888 or #3788.

Evil Ram

thanks for the replies, i'll be sending it back then, i just hope they take it back

ofcmarc

The Autometer won't pick up the signal from an I/C model harness either. The signal voltage is too low. But it looks good.....



Too bad it isn't any more accurate than listening to the rattle under the hood to determine engine RPM.
Wanna's advice is probly best in this case.....

Crossy's son

I don't know what your planning on doing with the truck. But a 5000 rpm tach is not necessary on a VE pumped truck. autometer #2888 1/16 tach like the one above in the picture is pretty sweet.

ofcmarc

Except it dosent work correctly.......

Crossy's son

You mean hooking it up to the factory harness?

Our 91 had a autometer 2/16 4000rpm tach in it that was hooked to the alternator.

93John

Really. How so? I had a 2888 with the alternator probe, it never worked right. The only time it would read steady was with a load on the alternator. Then it was still 200 rpm off.

gear jammer 91"

I have the autometer 2888 and it works great and it's accurate. All you have to do is adjust it.

Philip

That tach shown in the post was just thrown into that gage pod to fill the hole for the pic. I took that pic a couple of years ago. Some people wanted to see that 94 gage pod installed and a view of the speedo. Some had concerns about blocking the speedo to much.

BTW that tach will not work on a 5 volt signal.

Jim Lane

Has anyone used a Diesel tachometer and connected it to the AC tap or "R" terminal of the alternator?

That is how it is done in semi tractors.

Since I have a 3-phase output on my alternator this seems like it would be the right thing to do.

http://www.sw-performance.com/products/CTGDieselTach

http://www.sw-performance.com/index....=faq&id=6&q=65

I know the Auto meter Tachometer connects to the alternator but it is converting the frequency of the rotor through a pickup clamped around the laminations.

The AC or “R” type converts a portion of the alternating current into a usable signal.

VDO also has a tachometer that will connect to the “R” terminal.

http://www.egauges.com/pdf/vdo/0-515-012-037.pdf

Is there any option to install a mechanical tachometer drive to our engines? Then there are a lot of nice marine tachometers available that need a mechanical drive.

http://www.greatlakesskipper.com/pro...fm?CatID=SS224

Jim