2155 Tachometer and Hour meter not working

I just bought a used 2155 and the Tachometer and Hour meter are not working. I've searchd the parts catalog, and traced alot of wires. However I have not found a clear answer.

I've found 2 wire connectors (one is Brown, the other is Yellow-Black) near the Alternater that are just hanging.

There is a spot to plug 1 wire connector onto the alternator. This alternators website seems to indicate the Tachometer is run off of the alterntor (http://heavyduty.boschautoparts.com/SiteCollectionDocuments/2212161_UnivAltCat06.pdf)

Before I plug something in that I'm supposed to, do any of the other 2155 owners know if this is supposed to run the tachometer?

If yes, which wire should be plugged in?
Thanks

Tack runs of a pick up in the timing chain cover.

It depends. Some utilities do drive the tack from the
alternator. Some 40 series tractors for certain.
I would believe the JD parts book and service manual
before some guess by a guest.

(quoted from post at 08:59:09 08/01/12) It depends. Some utilities do drive the tack from the
alternator. Some 40 series tractors for certain.
I would believe the JD parts book and service manual
before some guess by a guest.

Click to expand...

Here you go buickanddeere AR96480 SENSOR. This is from PC 4217 - 2155 and 2355N Tractors (North American Edition) - 01Jul10

Here's a list of all the engines JD states that uses that sensor


1563 - 6619AF, 6619TF-01 OEM Engines and Accessories (Waterloo) - 13Jul11
1666 - 6620 Combine - 23May11
1667 - 7720 Combine - 23May11
1668 - 8820 Combine - 29Jul11
1721 - 6466D,T,A (s.n. 067685- ) OEM Engines and Accessories - 22Aug11
1746 - 6622 Combine - 23May11
1760 - 2440 (341000- ) Tractor - 16May11
1761 - 2640 (s.n. 341,000- ) Tractor - 16May11
1762 - 2940 Tractor - 16May11 ( FR DE )
1763 - 2040 Utility Tractor (350000- ) - 16May11
1764 - 2240 (350000- ) Tractor - 16May11
1776 - 8955T and 8955A OEM Engines and Accessories - 29Jul11
1903 - 8440 and 8640 Tractors - 13Apr12
2011 - 3430 and 3830 Self-Propelled Windrowers - 11May11
2074 - 5730 and 5830 Forage Harvesters - 11May11 ( FR DE )
2182 - 6076 (s.n. -499999) OEM Engines (Waterloo) - 10Aug11
2330 - 6076AFM Marine Engine and Accessories (Waterloo)(ESN -499999) - 02Aug11
2337 - 4039DFM01 and 4045TFM01 Marine Engines and Accessories (Dubuque) - 02Aug11
2367 - 6068DFM01 and 6068TFM01 Marine Engine - 18Jul12 ( FR )
2380 - 6076AF, HF, FT, AFN-30 OEM Engines - 02Aug11
2385 - 6101AF010, 6101HF010 OEM Engines - 02Aug11
2727 - 6.8L PowerTech Marine Engine (6068SFM50 / 6068TFM50) - 15Jun12 ( FR DE IT ES SV )
3153 - 4239D, 4239T, 4329A (3.9L) OEM Engines (Saran) - 10Oct11
3154 - 6359 OEM Engine and Accessories (CD-Saran) - 05Oct11
3178 - 3179 Repower and OEM Engines - 05Oct11
3191 - 4039 Repower and OEM Engines (Saran) - 05Oct11
3192 - 6059 OEM Engine and 6059DF092 Repower (100000-499999) - 05Oct11 ( FR DE IT ES SV )
3197 - 4045 OEM Engines and 4045DF/TF092 Repower Engine (100000-499999) - 05Oct11 ( FR DE IT ES SV )
3203 - 6068 OEM Engines, 6068TF092 Repower Engine (100000-499999) - 05Oct11
4172 - 940, 1040, 1140 Tractors (European Edition) - 21Jul10 ( FR DE IT ES SV )
4173 - 1640, 1840, 2040 Tractors ( -429999) European Edition - 21Jul10 ( FR DE IT ES SV )
4174 - 2040S, 2140 Tractors ( -429999) European Edition - 21Jul10 ( FR DE IT ES SV )
4175 - 3040, 3140 Tractors ( -429999) European Edition - 21Jul10 ( FR DE IT ES SV )
4182 - 2150 and 2255 Tractors (North American Edition) - 15Jul10
4184 - 1640, 2040, 2040S Tractors (430000- ) - 21Jul10 ( FR DE IT ES SV )
4185 - 2140 Tractor (430000- ) - 21Jul10 ( FR DE IT ES SV )
4186 - 3040, 3140 Tractors (430000- ) - 21Jul10 ( FR DE IT ES SV )
4187 - 2350 and 2550 Tractors (North American Edition) - 16Jul10
4188 - 2750 Tractor (North American Edition) - 16Jul10
4189 - 2950 Tractor (North American Edition) - 16Jul10
4190 - 840 Tractor (s.n. -599999) European Edition - 16Jul10 ( FR DE IT ES SV )
4200 - 3640 Tractor - 15Jul10 ( FR DE IT ES SV )
4206 - 3640S Tractor (FOR SPAIN) European Edition - 16Jul10 ( FR DE IT ES SV )
4207 - 3150 Tractor (North American Edition) - 15Jul10
4209 - 3050, 3350 Tractors (European Edition) - 25Jun10 ( FR DE IT ES SV )
4210 - 2650, 2650N, 2850 Tractors (Synchro-Transmission)(European Edition) - 01Jul10 ( FR DE IT ES SV )
4211 - 2250, 2450 Tractors (Synchro-Transmission)(European Edition) - 01Jul10 ( FR DE IT ES SV )
4213 - 1350 Tractor (European Edition) - 30Jun10 ( FR DE IT ES SV )
4214 - 2955 Tractor (s.n. -767516) North American Edition - 30Jun10
4215 - 2755 (GPT) and 2855N Tractors (North American Edition) - 01Jul10
4216 - 2355 and 2555 General Purpose Tractors (North American Edition) - 01Jul10
4217 - 2155 and 2355N Tractors (North American Edition) - 01Jul10
4223 - 2250, 2450, 2650 Tractors (Collar Shift Transmission) (European Edition) - 30Jun10 ( FR DE IT ES SV )
4224 - 1950, 1950N Tractors (European Editon) - 30Jun10 ( FR DE IT ES SV )
4225 - 3650 Tractor (European Edition) - 25Jun10 ( FR DE IT ES SV )
4226 - 3155 Tractor (North American Edition) - 25Jun10
4246 - 3055, 3255 Tractors (North American Edition) - 25Jun10
9686 - 6466 AG Application Engines - 10Jun08

Timing CHAIN?....

1640 here has the Bosch alternator and uses a tach terminal
which sends the rpm signal.
Can't get to a proper Internet connection to check if Delco
equipped tractors use the cam sensor to drive the tach?

(quoted from post at 10:19:39 08/01/12) 1640 here has the Bosch alternator and uses a tach terminal
which sends the rpm signal.

Click to expand...

Both these serial number break 1640's show they use AR96480 sensor and don't mention alternator type. According to my research 1640's only came with a Bosch alternator no Delco-Remy alt as an option.
4173 - 1640, 1840, 2040 Tractors ( -429999) European Edition - 21Jul10 ( FR DE IT ES SV )
4184 - 1640, 2040, 2040S Tractors (430000- ) - 21Jul10 ( FR DE IT ES SV )

It's a mystery then. The factory 35 amp Bosch quit on my
1640 and a new 55 amp Bosch from Deere cost nearly the
same as a rebuild. I clearly recall wondering why Deere and
Detroit diesel would drive some electric tachs from a little bitty
terminal on the alternator. While installing the tach wire onto
the alternator.
May have take a picture and post it?

If ever get the time or inclination you have your camera out to take a photo of the Bosch alternator also PLEASE take a photo of the LH frt side of the 1640 timing gear cover.

With the help of all of the other comments, I think I got this resolved.
Here are the steps I took.

1) Located the sensor (Magnetic Timing Sensor for Aluminum Timing cover).

2) Unplugged the wire and tested the continuity of the wire with a battery and voltmeter. (tested = OK)

3) Hooked up a wire lead and voltmeter to the sensor. Started the tractor, tested the sensor at idle. (test = BAD)
Took the throttle up to 3/4, tested the sensor. (test = BAD)

4) The John Deere parts catalog no longer supplies this part. Since the part would probably be really expensive, and Tachometer didn't work anyways, I decided to try plugging it into the Alternator’s terminal.

The Tachometer started working. I'm assuming it is accurate because at full throttle it does not go past the Max RPM guide numbers on the Tachometer. I also left the tractor running to verify the wire did not get hot and melt.

Regardless of the accuracy, I had no Tachometer to start with and now it should be reading fairly close to accurate.
(The original wires mentioned are for a different component. I’m not sure what it is used for, but it is not relevant for the Tachometer)

Sorry for not including pictures, but the forum won't let me post BBCode.