yo RR,
Did you check for Codes yet?
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?&pid=74587&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.
DIAGNOSTIC TROUBLE CODE CHARTS
Also post code(s) here by
KOEO & KOER
Didn't I see this issue on the PSOM jumpin' around w/slam shifting & Loos of speed previously? Here or in another Bronco Forum?
Is AMBER (Yellow to some) ABS LIGHT LIT?
Is TCIL (OD ON?OFF LIGHT at end of stalk Blinking?
Here are some possibilites;
Get the extra fluid put asap; do not want to cavitate fluid
transmission is leaking fluid out the front, One of three conditions has likely happened. 1. The transmission too much fluid and was venting through the front pump 2. The transmission overheated and was venting fluid through the front pump 3. The front pump seal is bad. Replacing the front pump seal is not involved once the transmission is out. Simply remove the old seal and install the new one. Purchase the seal from Ford..."
Source: by Ian L
Fluid Level Low, Low Transmission Fluid Level And Or Shift And Or Engagement Concerns TSB 97-12-13 for 87-96 Bronco & many others; "...transmission may have low fluid level and/or may have either a shift concern and/or an engagement concern. This may be caused by transmission fluid leaking from the transmission into the transfer case through the transfer case input seal. Replace the transfer case input seal..." read more
Source: by Ford via thedieselstop.com
Check Fluid Level and Condition
Before buying any parts;
This problem could be caused by a # of thangs;
bad vehicle speed sensor (VSS) (also called ABS,, DSS sensor) on da 8.8 (rear differential)/ or Connector/corroded wires inside connector;
or cruddy/damaged tone ring in the 8.8.
bad wiring/shorts /connectors from VSS at firewall, at 4WABS Module and /or at PSOM and then onto the PCM
bad 4WABS Module - It is located below ws wiper fluid/coolant recovery tank. So, the connector can be corroded by leaking fluid
bad PSOM (Speedo)bad wiring/shorts /connectors from VSS at firewall, at 4WABS Module and /or at PSOM and then onto the PCMthe locations of the connectors along the path from VSS to 4WABS and up to Instr Cluster & PSOM are;
C404 VSS On rear axle sensor (A7) Terminals: 02
C205 LH rear of engine compartment, in safety wall (Fire Wall) Terminals: 24 In-Line
C202F & M LH rear of engine compartment, in safety wall (A8) Terminal: 7 In-Line
C119 LH front corner of engine compartment on 4WABS control module (E10),Terminals: 40
O/LB to:
C202F & M LH rear of engine compartment, in safety wall (A8) Terminal: 7 In-Line
C252 Programmable Speedometer/Odometer Module (PSOM), Behind top LH side of I/P, on PSOM (A7) Terminal: 12 Color: B at Pins 4
LG/Y to Splice S107 Engine control sensor harness, from C119 near T/O to G101 to PSOM Pin 5
C202 F and M
and spliced to Ground G100 (BK)
From PSOM Pin 7 (GY/BK) to Splice S246 Main harness, near T/O to speed control amplifier to
C185 PK/O @ PCM 5.0L Powertrain Control Module (PCM) LH side of safety wall, on powertrain control module (PCM) (C10) Terminal: 104 Color: GY
C185, 5.8L Powertrain Control Module (PCM) LH side of safety wall, on powertrain control module (PCM) (C10) Terminal: 104 Color: GY
C185 @PCM to C202 F and M
Splice 216 to Ground G200, Instrument Cluster ground is inside passenger side kick panel
and on to C185 @ PCM PIN 58 (GY/BK) and from Pin 46 to MLPS (TR) Pin 2
Verify PCM & MLPS wiring & Pin numbers using following WIRING DIAGRAMs by Ford via Steve83
(my eyesight is fuzzy again)
http://www.supermotors.net/registry/media/95931_1
Here is
ONLY a SHORT EXCERPT of the Pin-Point Testing Process by Ford;
Check Fuses 8 & 18 in Cab fuse block (lower left of dash by driver's left knee)
If no 12 v on Supply Side of each; look in Power Distribution Box (Located under the hood on the drivers side fenderwell, on driver's side of the air cleaner housing)
and check **** FUSES J & S
Fuse Block Diagram in a 94 Bronco & F-Series
Compare to your 93.
My 96's same symptoms were erratic until the 4WABS Module's microprocessors finally burnt-out. I had one go bad and 2 yard Modules were also bad; so I jumpered the Module out as Steve & Turbo Ghost describes below.
To bypass the 4WABS module @ it's harness's connector & feed the ABS signal directly to the PSOM,
Disconnect module (under coolant recovery /ws washer tank) & in connector, jumper LG/Bk to LG/Y, and R/Pk to O/LB..."
pic of the connector and jumpers; Continuity Test Through 4WABS Module Connector in 93-96; "...jumper 14 (CKT 530, LG/Y) to 21 (CKT 519 (LG/BK) & 39 (CKT 491 (O/LB) to 22 (CKT 523, R/PK)...";
http://img.photobucket.com/albums/v252/turboghost/ABSConnectorw-jumpers.jpg
by Turbo Ghost
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.
This is tuff to do; suggest using str8 pins to back probe the connector
================
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
============
Tone Ring Inspection; "Take off the rear diff cover. Check the Ring Tone gear. It is located on the left hand side of the ring gear. Look to see if any of the teeth have been notched (from debris floating around in the diff.) Usually a spider gear. If the ring tone gear has been notched, it will need to be replaced to fix your speedo reading. Jack it up and rotate the
tires to look for the teeth to be notched/broken/bent..."
Source: by Bighibbi at FSB
more VSS info in my site -
More 4WABS Info, Connector Location and pin out diagrams etc in my site
