Tachometer doesn't work

Tiny
GREENCHEVYMALIBU
  • MEMBER
  • 1992 DODGE DAKOTA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
This truck has been sitting for a couple years. It had a bad tranny. I would from time to time start it and drive it around my house and park it again. A few months back when I moved it the tach still worked. I replaced the tranny and now the tach doesn't work. What can I test? Also I replaced the fuel pump and it does register how much gas is in the tank. It doesn't move at all like the tach. Would either of these problems signal a check engine light? I drove the truck after the tranny change and it felt like it was shifting smooth. When the light turned on I felt no engine change. It is a dakota 3.9L V6. When the check engine turns on the tranny seems to not know when to shift. Ok I checked the codes and I got 12, 15, 55 but I think 12 and 55 mean nothing right? So 15 is vehicle speed/distance sensor circuit. How can I test this? I figure that this is why the transmission seems to shift erratically. Does this mean that its bad and I have to replace it?This was working on my original transmission. I took this sensor off my old transmission and put it on my replacement transmission. It worked on the old tranny the last time I test drove it but I guess in time things go bad.
Monday, September 21st, 2009 AT 8:40 AM

6 Replies

Tiny
IMPALASS
  • MECHANIC
  • 3,112 POSTS
Hello -

Thanks for the info. . .. . ..

Let's start with the fuel pump. . .. . .. . .. . ..I have the test below. . .. . .try to retrace putting the fuel pump in. . .. . ..the sending unit is attached, the float etc. . .. . ..it may be in a bind. . .are you sure all electrical connection were connected?

Do the test and see what you find there. . .. . .. . .. . ..

FUEL GAUGE & FUEL TANK SENDING UNIT TEST
NOTE: DO NOT leave sending unit lead grounded for extended periods; gauge damage will result.
Dakota
1. Test fuel gauge and wiring by grounding fuel tank sending unit lead. Turn ignition on, and note gauge reading. DO NOT leave sending unit lead grounded for extended periods; gauge damage will result.
2. If gauge indicates maximum reading, wiring and fuel gauge are operating properly. Go to step 4). If gauge does not indicate maximum reading, remove gauge. Using a voltmeter, check for battery voltage between B+ pin and ground pin. See Fig. 1.


https://www.2carpros.com/forum/automotive_pictures/248015_F1_8.jpg



Fig. 1: Identifying Instrument Panel Gauge Pins (Dakota)
Courtesy of CHRYSLER MOTORS.
3. If voltage reading is not as specified, check wiring connections and instrument panel printed circuit board continuity. If wiring and circuit board test okay, replace fuel gauge.
4. If gauge indicates maximum reading in step 2), remove fuel tank sending unit. Connect a jumper wire between sending unit body and chassis ground. Install sending unit harness connector. Move float arm to FULL, then EMPTY position. Note fuel gauge readings at each float arm position. Allow at least 2 minutes at each test point for gauge to stabilize.
5. If no reading or improper reading is obtained at either test position, replace sending unit. If sending unit tests okay, check for damaged ground wire or poor connection. Ensure float assembly does not bind in fuel tank and tank is not damaged. Repair as required.

Was the fuel and tach working prior to the tanny R&R?

Code 15 is NO VEHICLE SPEED SIGNAL No Distance Sensor Signal Detected During Road Load Conditions. That is located on side of the transmission. . ...check the connections. . .the sensor may be defective.


https://www.2carpros.com/forum/automotive_pictures/248015_sensor_1.jpg



The Tach. . ...the computer controls this. . .check Fuse 6, 15 amp with an ohm meter and see what you have.

6 - 15 Amp (Lt. Blue)

Horn, Tachometer.

TACHOMETER (DAKOTA)

SBEC provides signal to drive tachometer on Dakota. SBEC Single Board Engine Controller

Unless you have the proper equipment you may not be able to check that. Check the suggestions below.

SINGLE BOARD ENGINE CONTROLLER (SBEC)
Harness Check
1. If SBEC is found to be faulty during SELF-DIAGNOSTICS testing, perform following steps to confirm diagnosis. Most components are incorrectly diagnosed due to faulty electrical connectors or poor connections between component and vehicle. Sometimes, simply disconnecting and connecting an electrical component will provide a good electrical connection.
2. Before replacing an SBEC, check all components in suspected circuit. If components are okay, carefully disconnect SBEC from vehicle harness.
3. Inspect SBEC harness connector and SBEC contact pins for corrosion, bent pins, missing pins, spread cavities and broken wires. Clean, repair or replace connector as necessary.
4. Connect SBEC harness connector to SBEC, and retest system using Diagnostic Readout Box (DRB-II) or similar scan tool. See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section. If vehicle does not pass test and fails with same message, replace SBEC.

I apologize I don't have a test for the sensor other than with equipment. . .. . ...

You are correct. . ..55 is that is the end. . .. . .. . .. . ..12???? don't have that one. . ...could that be a miss count??
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Tuesday, September 22nd, 2009 AT 8:08 PM
Tiny
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Thanks for the help i'll let you know what I find out after the tests.
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Tuesday, September 22nd, 2009 AT 9:37 PM
Tiny
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  • MECHANIC
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Hello -

Sounds good. After sitting for so long... You really need to look the wiring over really good... Like at the computer, behind the dash cluster. Plugs can be corroded or not sure if you are near mice etc, but they can chew through things. Saw a Mercedes Benz with a nest in the engine bay all nice and neat in the fuse box!

You are defiantly on your way... You got the big thing... The tranny... So there is bound to be a little tweaking etc.......

Also look at the fuses really good for corrosion
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Tuesday, September 22nd, 2009 AT 10:15 PM
Tiny
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  • 230 POSTS
The speedometer was broken so I fixed that so the tach works now and no check engine light. But now the it seems that there is a problem with the tranny. It doesn't feel like its slipping it feels like the shifting is off. It shifts from first to second fine second to third fine but third to fourth its starts to high rev then shift. I was thinking if this seemed like it might be worn bands in the tranny? Maybe in need of re-adjustment? The tranny has 170,000 miles on it. The tranny seems fine other then that.
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Sunday, October 4th, 2009 AT 5:03 PM
Tiny
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I was told that maybe it could be sludge. Sticking the clutch plates
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Sunday, October 4th, 2009 AT 6:35 PM
Tiny
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  • MECHANIC
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Hello -

I would find a reliable transmission place and let them do a good flush on it since it has been sitting so long... Filter change.

Many times depending on the model..... The computer has to learn the driving conditions... It may have sat for so long..... It is relearning..... You can ask the transmission place.
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Sunday, October 4th, 2009 AT 8:07 PM

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