I have a 1993 Ranger with a 3.0 v6 5 speed and when I start accelerating the tachometer is fine until i hit around 2500-3000 rpm and then it will start to drop even when still accelerating. Anyone have any ideas i dont really want to tear apart my dash but if thats the case i will. Thanks

 

At work now. Give me some time and I will post some troubleshooting suggestions.

 

Okay great thank you

 

Sorry for delay.


From the 1993 Ford Service Manual:
The Tach has 4 connections labeled on the instrument cluster PCB as:
1. SIG (EDIS Tach Signal In)
2. IGN (Power from Ignition Switch)
3. GND (Ground)
4. 8 (Grounded for 6 cylinder trucks.)

The first step in troubleshooting is Is tach inoperative?
Yes. Check fuse. Is fuse ok? No-- replace fuse. Yes-- continue troubleshooting.

Second step
Check for loose wiring connections in engine compartment and instrument cluster.

Instrument cluster connection is a vertical connector that is located on the left side of the cluster as seen from the rear.

For a 3.0L the under hood connections for the Tach Circuit (Circuit 11) are:
• Connection 250 Pin 8 at the instrument cluster to connection 105 on the safety wall (firewall) to the right of the brake master cylinder. 53 terminals, white connector.
• Connection 105 to splice 116. I do not have a location for splice 116
• Splice 116 to C172 at the top right hand side of engine at ignition coil, 3 terminals, brown connector, and C1006 Pin B at the ignition control module located on front driver side radiator support, 6 terminals, gray connector.

Is wiring ok? No – Secure loose connections. Yes – continue troubleshooting.

Third step
Disconnect battery ground cables, remove instrument cluster and using an ohm meter make the following resistance checks:
• Connector 250 Pin 2 resistance to chassis ground. Reading should be 1 ohm or less.
• Connector 250 Pin 8 to Connection C1006 Pin B. Reading should be 1 ohm or less.
• Connect battery. Turn ignition switch on. Check for +12 volts at Connector 250 Pin 14. Turn ignition off and disconnect battery.

Are all measurements within spec? Yes – replace tach. No – Condition is not in tachometer, service wiring.

Pinouts:

C250
____
14 | | 1
13 | | 2
12 | | 3
11 | | 4
10 | | 5
9 | | 6
8 |____| 7

1 = Right turn signal
2 = Tach Ground
3 = Cluster Illumination
4 = High Beam Indicator
5 = Fasten Seatbelt Indicator
6 = Not Used
7 = Not Used
8 = Tach Signal Input
9 = Tach Ground
10 = Brake Indicator Input
11 = 4x4 Hi Indicator
12 = 4x4 Lo Indicator
13 = Anti-Lock Brakes Indicator
14 = Power (Start or Run)

C1006
___
A| |
B| |
C| |
D|_ |
E| |
F|__|

A = From Distributor
B = Tach
C = 12 volt Start or Run
D = From Powertrain Control Module
E = From Powertrain Control Module
F = From Powertrain Control Module

 

Thank you i appreciate the help

 

Perfect! I was about to ask this question... my tach is in and out at random times.

Only thing is, I tired to remove the cluster and I believe it's the speedo cable preventing me to pull it out. It's so tight, I can't even get my hand behind it to take it off... what am I doing wrong?

Thanks for the help.

*Edit: I have the 4.0L V6... is there a different wiring harness for it?

 

I have a 1993 ford ranger 4.0 sport and the oem tach goes in to the negatives when I go to accelerate and at idle it sits at 500 rpm I'm just asking how do I fix this issue

 

Welcome to FTE

You've resurrected a 10 year old thread but will see if I can get things started.

See above trouble shooting post #4
Did the problem come about suddenly after some event ???
Loose, Corroded, Rusty or otherwise Faulty grounds, or loose / corroded electrical connector, or its pins / sockets connections or wire crimps, probably belong on the suspect list. So inspect, thump & wiggle test, to see if things will wake-up & function.
Some beginning thoughts for consideration, let us know what you find.

 

I’m wondering if the stepper motor for the tach has lived a good life and is calling it quits.

I swapped a tach cluster into my old ‘94 Ranger and whatever gauge at the top left would go “negative” at times on startup. I’d flick it and that worked. Of course, unlike the tach, that was just a fake gauge, so it usually was either off or pointing at the middle, more or less.

If I was in your spot, I’d just swap in a new cluster. The speedometer section pulls out and you swap into the new cluster. You keep your current mileage. Voila!

If you go that route, I’ve heard some of these are 4.0 engine specific. I think the cluster will have a label if that’s the case. My Ranger was a 2.3, but the Explorer obviously had a 4.0. Worked fine.