Speedo jumping around

[wdford]

I read and searched... my odometer is very close to my GPS. My ABS is working fine and I checked my VSS sensor, plug and ring. I just want to make sure that this is the common issue. FWIW the only other problem is that my cruise control surges badly.

see video below

BQ4EPItekws

[Alvin in AZ]

Originally Posted by wdford

"Speedo jumping around"
{plis}
...other problem is that my cruise control surges badly.

I had exactly those two symptoms at once too.

Mine was caused by a badly worn speedometer driven gear.
Pull yours and look at it and let me know if yours is worn too? :)

Alvin in AZ

[wdford]

Iirc it's electronic... Still has a gear somewhere inside?

[sackman9975]

Originally Posted by Alvin in AZ

Mine was caused by a badly worn speedometer driven gear.
Pull yours and look at it and let me know if yours is worn too? :)

Alvin in AZ

1992-1996 run off the tone ring. So no speedo gear.

You probably have one of these three issues:

• Bad spider gears that are chewing up your tone ring

• Bad VSS

• Or your ABS module is going bad

First, pull the VSS out of the rear axle and peek through the hole to check the teeth on the tone ring, make sure to check it 100% revolution......or remove the cover off the diff.

If the tone ring looks fine, then you'll probably want to jumper the ABS module. Read this great thread by Turbo Ghost to show you how

[Kingfish999]

if the fluid is full of metal particles it can mess with the signal. changing the fluid usually fixed it for me till it happened again

[wdford]

Originally Posted by sackman9975

1992-1996 run off the tone ring. So no speedo gear.

You probably have one of these three issues:

• Bad spider gears that are chewing up your tone ring

• Bad VSS

• Or your ABS module is going bad

First, pull the VSS out of the rear axle and peek through the hole to check the teeth on the tone ring, make sure to check it 100% revolution......or remove the cover off the diff.

If the tone ring looks fine, then you'll probably want to jumper the ABS module. Read this great thread by Turbo Ghost to show you how

I had the diff apart the VSS ring was in perfect shape. I'll jumper the plug and see what's up but no ABS light is on.

Originally Posted by Kingfish999

if the fluid is full of metal particles it can mess with the signal. changing the fluid usually fixed it for me till it happened again

Did that.. the fluid looked like a metal slushy. I cleaned out the entire diff before putting the cover back on... no change :(

[Kingfish999]

doe it only happen at higher speeds? might wanna replace the VSS since its cheap and easy

[wdford]

Originally Posted by Kingfish999

doe it only happen at higher speeds? might wanna replace the VSS since its cheap and easy

All speeds... it's not the ABS computer, still jumps, so we're going to pull the VSS sensor out of my dad's 1996 F150...

[wdford]

Installed a known good VSS and jumped around the ABS computer, still jumps. VSS ring looks good... some edges are rounded but the top of the ring "teeth" all look good and sharp. :dunno

[BRONCONUT]

We replaced the whole PSOM in another truck and fixed it after looking at the tone ring and bad sensor.

[wdford]

Originally Posted by BRONCONUT

We replaced the whole PSOM in another truck and fixed it after looking at the tone ring and bad sensor.

Thanks . . I guess its a trip to P&P tomorrow!

[dgarvy]

I had a similar problem before my speedo cable broke in my 90, but I'm not sure how that will relate to your 95. good luck

[Alvin in AZ]

Posted by Alvin in AZ:
Mine was caused by a badly worn speedometer driven gear.
Pull yours and look at it and let me know if yours is worn too? :)

Originally Posted by sackman9975

1992-1996 run off the tone ring. So no speedo gear.

Heck, I was really thinkin' I had that one nailed too. :/ LOL

Butthead in AZ

[miesk5]

yo,
As SACKMAN cited TurboGhost's ABS Module jumper post. see my reply in ther;

there could be other factors causing the PSOM needle to jump; such as;
a damaged ABS tone ring/or shavings in the rear differential
a bad ABS (also called VSS) Sensor or it's connector/wiring (corroded connections/conductors)
other connectors along da path
electr path from VSS (ABS/DSS) Sensor to PSOM...
From VSS Tone Ring & Sensor to its Connector
to Firewall connector
to 4WABS Module Connector and into 4WABS Module & out thru 4WABS Module Connector
into Firewall connector and then to PSOM Connector and thru PSOM
and then to Cruise Control Servo/ Amp if equipped

and also to EEC (PCM) and then to E4OD.



Have you checked for Codes yet?
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-co...mode__threaded


The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:
KOEO
&
KOER

[wdford]

Thansk miesk5 -

KOEO - 27 and 34, VSS sensor was unplugged for some testing. My Bronco's sensor works fine in my dads F150 but I ordered a new one anyway.

KOER - 526 and 528

[miesk5]

yo WD,
How is the tranny shifting or operating?
Does OD Light blink while driving?
Is Amber ABS Light on too?


You should have only 3 digit codes
526 Neutral Pressure Switch closed or A/C on


528 Clutch Switch Circuit failure (proby
DTCs 522, 525, or 528 resulted from the voltage being high at either:
Pin 10 = A/C input
Pin 30 = PNP/CPP input
while cranking the engine or during Key On Engine Off Diagnostic Test Mode (DTM).
Possible causes:
A/C circuit shorted to power.
CPP circuit open.
PNP open.
Damaged PCM.
Starter relay disconnected during Self-Test.
Clutch Pedal Position (CPP) Switch jumper may be off the connector

Wiring Diagram in a 95; from ign switch through CPP to PCM


Starting System Wiring Diagram in a 95; from Ignition Switch through Clutch Pedal Position (CPP) Switch and CPP Jumper to Connector C103F (LH side of engine compartment, top of wheel well, Terminal: 16 Color: BK)

Source: by Seattle FSB (SeattleFSB)


Clutch Pedal Position (CPP) Switch Removal & Connector Pin-Out W/Logic Table & Parts Break-Out Diagrams in 87-96



---

See my post @ http://fullsizebronco.com/forum/showthread.php?t=201477
for typical PSOM waver testing & info;
such as;
For reference purposes:
PSOM Pointer PSOM Pointer Waiver TSB 96-21-11 for 92-96; "..The speedometer needle may waver and or a light surge may occur on some vehicles..." read more
Source: by Ford
This also addresses the tone ring & PSOM unit
EXCERPT; ISSUE: The speedometer needle may waver and/or a light surge may occur on some vehicles when speed control is used at highway speeds between 80-113 km/h (50-70 mph). This may be due to slight dents/chips in either the exciter ring or the Vehicle Speed Sensor (VSS) and air gaps between the VSS and the exciter ring.

ACTION: Replace the Programmable Speedometer/Odometer Module (PSOM) if required. New PSOM's come with increased immunity to system variability. Refer to the following Diagnostic Procedure for details.

DIAGNOSTIC PROCEDURE
BRONCO/F-SERIES - Perform normal PSOM diagnostics per Pinpoint Tests "H" and "J" of the 1996 F-Series/Bronco Body/Chassis Service Manual, Pages 13-01-30 through 13-01-32 and Pinpoint "B" of the 1996 Powertrain/Drivetrain Service Manual, Page 10-03-11.

Any slight dents, chips, etc., in either the exciter ring or VSS will create needle waver. Measure air gap between the VSS and exciter ring. It should be 0.38-0.51mm (0.015-0.020"). Check exciter ring runout per the same ring gear backface runout procedure of the appropriate model 1996 Powertrain/Drivetrain Service Manual, Section 05-00. Make sure the exciter ring is mounted correctly to the ring gear. If runout is more than 0.1mm (0.004"), perform the differential runout check per the procedure in the appropriate model 1996 Powertrain/Drivetrain Service Manual, Section 05-02A or 05-02D, to find cause and repair as needed

--
Speed Input Signal Test @ PSOM in 93-96 Bronco; "...NOTE: Only wiring harness end of connector is to be probed. * Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in ) and Pin 5 (speed in -). * Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)? OR: If available, a frequency counter may be connected to Pin 4 (Speed in ) and Pin 5 (Speed in -). Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)? OR: * If neither a voltmeter nor frequency counter is available, vehicle speed control may be used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor & tone ring can be assumed to be good.
by Steve83
This is tuff to do; suggest using str8 pins to back probe the connector

[wdford]

Originally Posted by miesk5

yo WD,
How is the tranny shifting or operating?
Does OD Light blink while driving?
Is Amber ABS Light on too?

Truck runs great, no blinking lights or ABS lamp. The only issue I am having is the jumpy needle and when the cruise control is engaged it does surge as stated lower in your post.

Based on the idea that the CC runs off the VSS I must have a faulty ring. All I had checked on the VSS ring was that all the teeth looked good which they did. However the post stated that runout must also be checked and with 220k miles on the rear end this could be the issue.

I am going to have new gears and a locker installed so it will be a good time to replace the VSS ring too. I will try a different PSOM just for grins though.

[wdford]

the fix was replacing the gauge cluster.. it's ultra smoove now

[BroncoBuff777]

what did that cost? im sure ill be needing one.

[miesk5]

Originally Posted by BroncoBuff777

what did that cost? im sure ill be needing one.

yo BroncoBuff,
If you test and find you need a PSOM or want a cluster; try local yards; pay less than $75.00 for a cluster w/$ back guarantee.
If you go that route and want a cluster w/Tach, then this is the time to decide what to buy.


For a YARD SEARCH on-line, I use;
http://www.mypartshop.com/
Select All Parts
year, etc, then FORD TRUCK
Select;
Instrument Cluster
&/or
Speedo Head/Cluster

or
http://www.copartfinder.com
Has Vehicle Pics!

http://www.picknpull.com

http://www.car-parts.com/

A Very Goog PSOM/cluster rebuild shop is DNA Speedometers, Inc.
Tampa, FL 33614
http://www.dnaspeedometers.com/
"...we offer a One Year Warranty. If you have any problems within that period of time, we will try to fix it or you are guaranteed your full money back..."
They are reliable, call them if needed. Thay also have an Online Quote feature