I'm having an odd, come-and-go issue with my Ranger (1999, 3.0L v6 Flex, 2x4, XLT, Auto, 145k, Well maintained). My truck will occasionally have an electrical issue that causes a arrhythmic clicking/snapping sound from inside the dash behind the instrument cluster. This sound is audible before I put the keys in the ignition. Once I do put the keys in the ignition, my door ajar light and tone, as well as the cabin light, will go on and off in sync with the nose from the dashboard. When driving with the issue, my speedometer and odometer are completely non-functional and the automatic transmission is jarring when moving between 1st-2nd and 2nd-3rd gear. The O/D light on the dash will also sporadically flash.

I was initially getting codes related to the vehicle speed sensor and thought it might be a related issue, but that went away when I resolved a cylinder 2 misfire by replacing my spark plugs. I also saw some saying the issue could be related to the #25 fuse, but replacing the fuse (which had no visible damage) hasn't resolved the issue. I am not getting any codes and my check engine light is off. My fluids are fine.

The weirdest part to me is that the issue is extremely inconsistent - it will appear every few weeks, sometimes while I'm driving but usually I get in and the sound is already there. It will stick around for 24-48 hours, during which I generally avoid driving, and then go away for a week or two. It doesn't seem to be associated with how much I've been driving or the temperature.

Has anyone experienced similar issues? I have seen reports of similar noises from the dash, but mostly affecting A/C or other systems. My A/C seems unaffected.

 

Welcome to the forum

1995-2003 Rangers use a GEM Module as the Body computer, it runs all the electric systems in the cab

1998-2000 Ranger GEMs also ran the Speed signals to speedometer, computer and cruise, but just those 3 years

Without a reliable speed signal computer can't shift automatic transmission very well
So in a 1999 Ranger if speedometer is erratic then computers speed signal will be as well, so rough shifting

You have a Battery Saver relay in a "Relay Box" just above the gas pedal, battery saver relay powers most lights in the cab
GEM controls this relay, it turns it off once key is out and both doors are closed, but after 20-30min, there's a timer delay, it would prevent battery from dying if a cab light was left on
As soon as you open either door the GEM activates the battery saver relay and the Dome light should come on, along with Door Ajar light
You could have a bad drivers door switch which is shorting open/closed, open/closed,ect.... which will cause that clicking and dome light to pulse
If there is no "clicking" at the moment then open passenger door and see if dome light comes on and stays on normally,no "clicking"

The "clicking" noise is most likely the battery saver relay, but this relay has no connection to speed signal
System they both have in common in 1999 would be the GEM module

GEM has 4 fuses in cab fuse box, 10, 20, 25 and 28, all 7.5amp, pull out each one and make sure its OK and no corrosion on the legs/terminals

Next will be to check Relay Box 1 above gas pedal, the box is attached to the side of the center console with its back side facing radio, so it faces out towards parking brake pedal, it has a plastic cover that comes off, inside will be several relays, layout depends on your Ranger's options, so different in each model group
Example lay out here: https://cimg8.ibsrv.net/gimg/www.ran...f26c9b27c1.jpg

If its the battery saver relay that is "clicking" you should be able to pin point that relay by cycling key off and on to cause it to "click"


GEM module is behind the radio so a bit of work to get to
These are year and model specific
It will have a part number on it starting with XL5T-14B205-??
You need to match the XL5T and ??
The 14B205 is the same number for all GEMs in any Ford model, so most of the time its left out
XL5T = 1999 Ford Ranger
YL5T = 2000 Ford Ranger
F87T =1998 Ford Ranger
Any of these years GEMs "should work" as long as its from/for a 2WD Ranger not a 4x4

You can take apart the GEM and clean it or look to see if the circuit board has any damage, also inspect the connectors and wires for corrosion or damage

 

Thank you!
I swapped out the PCM relay on a friend's advice but the issue has returned. I am not seeing anything related to door opening/closing - today the clicking returned after the car started. As soon as I have time I will go through the fuses in the cab box relevant to the GEM and try to figure that out. If that does not resolve my issue I will check the relays above the gas pedal. I am inclined to say this isn't a battery saver issue because it is not related to putting the key in the ignition and it is causing this speedometer issue.
I'll return here once I have more info to report.

 

The on and off dome light when "clicking" that you mentioned would be related to battery saver relay clicking on and off, it powers the dome light circuit
But its controlled by the GEM
A 12volt relay with click off and on when its voltage is cut and restored, of course, but also if the voltage drops below, say 6volts, its not exact

 

So far the problem hasn't reared its head, so it's hard to pinpoint it.

I've gone through and checked fuses 10, 20, 25 and 28 and all are fine. I got into the relay box above the gas pedal - I couldn't pinpoint any clicking noise coming from them, but went through and inspected all connectors and there was no corrosion or other issues.

The inconsistency of the problem is what makes it so hard to fix - I guess next time I experience it, I'll climb under the dashboard to see if I can hear one relay making the clicking sound?