Speedometer and odometer stopped working all of a sudden

BRIANWITHROW

MEMBER
1996 FORD BRONCO
5.0L
V8
4WD
AUTOMATIC
185,000 MILES

After getting gas a couple weeks ago I lost my speedometer and odometer suddenly and the overdrive indicator came on flashing. Did some research and just about everything I read pointed to the speed sensor on the differential I believe. I bought a new one and had it replaced but it didn't help. Also, the speedometer and odometer are numbers 8 and 18 on the fuse box and fuse 18 (10 amp) keeps blowing. I am considering selling it so I'd like everything to be working properly first.

Also, I have replaced the O2 sensors twice and the code says the O2 sensors need replaced. Why? I've replaced them twice and the Check Engine light still comes on.

Any help would be greatly appreciated.
Brian

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

Hi Brian,

Here are the wiring diagrams for the speedometer and odometer. You will see that these two are controlled by the same microprocessor and receive the input of the vehicle speed from the 4WABS module. So the question we need answered is if you replaced the wheel speed sensor, is the 4WABS module sending the signal to the Speed/odo module?

Basically, you need to go to pin 4 and 5 on the cluster and measure voltage while the vehicle is moving (or at least the wheels are spinning). If you are not getting the voltage here then you have a wiring issue. The fact that you have fuses that keep blowing points again to a wiring issue.

You can just unhook your cluster connector and measure for short to power/ground and measure resistance from the cluster to the 4WABS module. This most likely will show your wiring issue.

Let me know what you find with this and we can go from there.

As for the o2 sensor issue. Send me the codes that you keep getting because most likely if the sensor has been replaced but you keep getting a code, you either have a wiring issue or module issue. Most likely a wiring issue based on everything else that is going on here.

Thanks

https://www.2carpros.com/articles/how-to-check-wiring

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