Tachometer needle intermittent not working properly?

Hello,

The problem is either going to be with the Power-train Control Module, the instrument cluster itself, or the CAN system connecting the two together. In the diagrams down below I have included the diagnostic troubleshooting guide from the vehicle manufacturer for an intermittent tachometer. Please go through this guides and get back to us with what you find out.

Thanks,
Alex
2CarPros

Hey DAVID CONROY,

You have the 2.5L turbo diesel motor?

Were these faults present straight away after the replacement of the crankshaft pulley?

I do not have the details for that motor but the pickup for the crankshaft position sensor may be part of the pulley.

I would say returning to the garage to get them to recheck the fitting would be the first thing to do. I would be wary that if the bolt that holds the pulley has come loose and the pulley is starting to work its way off that driving it further could end up causing you some fairly serious engine damage.

Regards, Joe

Disable SRS system then remove the screws and pull the center instrument panel finish panel out from the instrument panel. Disconnect the electrical connectors and remove the radio and center instrument panel finish panel. Remove the screws and remove hood latch release handle. Remove the instrument panel steering column cover. Remove instrument panel steering column opening cover reinforcement. Position column gear shift lever aside, if equipped. Pull instrument cluster finish panel out from the instrument panel. Disconnect the connectors and remove the cluster finish panel. Remove the instrument cluster screws and disconnect and remove cluster. Twist and remove bulb needing replaced then reverse procedures to install.

Hello and thanks for donating

a slow and sluggish tachometer is normally due to faulty grounding of the tach. Since the original cluster didn't have a tach, there is no ground being presented at the cluster for a tach. An easy way to check is just get a loose piece of wire and ground it good to a bolt or something in the cab of truck, then wire it to the tach. If it works fine then you need to run a good permanent ground.

The speedo cable does not affect tachs, the tach is electronic while the speedo is manually driven by cable.

The tach circuit terminal connector ground pin is pictured below.. The tach uses the ignition coil to get its signal..

Yes, email sent, sorry about that.

Good to hear, please use 2CarPros anytime we are here to help.

Dual distributor? No such thing.

I assume you have the 8 plug, 2.3 engine.
The first thing you need to do is to determine if both sides of the ignition system are actually working. Test for spark at all 8 spark plugs. It's entirely possible for one side of the ignition module to be burnt out or failing for some external reason.

Hi,

It could be any of the above issues.

Lets start with this. I have a flow chart for testing. I will give you the start of it. Once you do this and let me know the results, I can move you to the relevant next steps.

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1994 Ford Truck Ranger 2WD L4-140 2.3L SOHC
KE1 - Check For RPM Drop
Vehicle Powertrain Management Computers and Control Systems Testing and Inspection Pinpoint Tests With EEC IV (OBD I-A System) Pinpoint Tests KE - Idle Air Control Control Solenoid KE1 - Check For RPM Drop
KE1 - CHECK FOR RPM DROP
Diagnostic Trouble Code (DTC) 412 indicates that during Engine Running Self-Test, engine rpm could not be controlled within the Self-Test upper limit band.

Possible causes:

- Open or shorted circuit.

- Throttle linkage binding.

- Improper idle airflow set.

- Idle Air Control (IAC) solenoid contamination.

- Items external to Idle Air Control system that could affect engine rpm.

- Damaged IAC solenoid.

- Damaged Powertrain Control Module (PCM).

- Key "OFF".

- Connect engine tachometer.

- Start engine.

- Disconnect IAC harness connector.

- Does rpm drop or stall?

Yes -- Go to KE2. See: Computers and Control Systems > Pinpoint Tests > KE2 - Check For Other DTCs

No -- Go to KE3. See: Computers and Control Systems > Pinpoint Tests > KE3 - Check For Other DTCs

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Also, here is the test for the tach not working

1994 Ford Truck Ranger 2WD L4-140 2.3L SOHC
R: Tachometer Always Indicates Too High or Too Low, No Tach Indication/Tach Indication Erratic
Vehicle Instrument Panel, Gauges and Warning Indicators Instrument Cluster / Carrier Testing and Inspection Pinpoint Tests Electronic Instrument Cluster R: Tachometer Always Indicates Too High or Too Low, No Tach Indication/Tach Indication Erratic
R: TACHOMETER ALWAYS INDICATES TOO HIGH OR TOO LOW, NO TACH INDICATION/TACH INDICATION ERRATIC
R1 CHECK WIRING

Make sure engine is not misfiring.

Disconnect battery ground cable

Remove instrument cluster.

Using Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent, measure resistance between connector B Pin 20 and coil.

Wiggle connections and wiring near coil to check for intermittent connection.

Is the resistance less than 100 ohms?

Yes

REPLACE instrument cluster. RECHECK operation.

No

SERVICE wiring Circuit 11 for open circuit.

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Let me know what you find,

Joe