This is just a test for possible inclusion into the Vanís forum Tech Folder. All are welcome to read it of course!
Recently a few threads have popped up concerning adding tachs to earlier E Vans. I thought to post an autopsy on the typical cluster as found on í97 and onward E-Series up to but not including the digital odometer display models. This is intended to be nothing more than an inside look, somewhat demystifying them perhaps, allowing someone to use this for DIY repairs.
Feel free to comment should there be any errors factual, electrically or your own actual experience. Iíve successfully repaired my own cluster with an inoperative coolant temp gauge. As with most excursions into fixing what was intended to only be replaced the learning curve here wasnít horrible.
This is presented as though disassembling the entire cluster and its sub-assemblies is the goal. Some repairs can be done without going this deeply into the cluster---your situation will determine what to remove or disassemble. Some of this may be more than youíd ever want to know however; just pick out the info most helpful.
Hopefully this is interesting and/or helpful somewhere along the way. So then we begin:
Typical cluster, clear mask removed, front & rear views:
6 tabs hold the mask to the cluster shell:
Releasing the mask tabs:
Remove all lamps (14 here) and the six 5.5mm screws which hold the cluster shell & face place together:
GENTLY lift the flexible circuit film from these 9 holding posts that double as locating pins:
This film is fairly tough and durable but caution is still important to not damage the solder traces which are just electrical conductors.
There is a PCB mounted to the cluster shell (3 T10 screws) and connected to the flexible circuit film:
The PCB connects to the flexible circuit film here:
Note: Red highlighted areas are locating points, shown for orientation of the different views. The PCB and flexible circuit film are VERY vehicle specific and must remain together in order to maintain the vehicles functions including speed, odometer and transmission shift commands from the ECM.
Three internal wiring connections need to be disconnected in order to continue disassembling the cluster.
First to disconnect is the PCB to the flexible circuit film shown above hightlighted by the black border.
(Arrows show locking tabs accessible as shown in Photo 8 above.
GENTLY lift each side to free the PCB from the circuit film. Two additional connections the the PCB can be removed:
Flat cable is for the gauge servo assembly; round bundle goes to the speedometer/odometer assembly (shown here separated from the cluster housing cables intact.)
(Above view shows potential problems from mishandling these components; locking tab for the flat cable connector broke away from the PCB. The connection will still be tight but its advisable to be careful to prevent this on the other connections.)
Once these 3 connectors are loose the faceplate and works of the cluster can now be removed from the shell, shown from the back side here:
(Its not necessary to remove the PCB from the faceplate. Various views show it removed for better camera angles.)
Servo PCB assembly held to the faceplate via (8) T10 screws:
Once the gauge servo PCB assembly screws are removed both it and the odometer assembly can be removed from the faceplate:
A closer view of the odometer and the trip meter resetting action:
Left image shows trip meter engaged, right image showing the driving gear disengaged, allowing the counters to reset and register 000.0. The highlighted shaft supports gears that turn each counter one full revolution until its close to reading zero again. A pin located in the left side of each counter wheel will engage an inner rib of the adjacent counter wheel causing that counter to register one number higher.
During reset fingers also mounted to the highlighted shaft push against each counter so they freely revolve to a place they display 000.0. This is purely a mechanical action and counters are not spring loaded so they donít ďunwindĒ when the reset lever is pushed.
Its possible to complete disassemble the entire trip meter and odometer down to its individual parts. Iíve done it myself. Being honest though it was quite a task, mostly trial and error which eventually resulted in a working cluster once again. The only item that would fail is the DC stepper motor, somewhat easily replaced as shown below. Replacing just the motor would allow you to maintain the present indicated mileage.
By gently lifting the tabs holding the motor to the odometer frame and twisting it counter-clockwise will release it.
Individual servos are soldered to the larger PCB, seem to be the same for water temp, oil pressure, fuel level and voltage. In theory it should be possible to desolder them from the PCB and replace with a known good servo.
This would be possible only if the cluster is disassembled as shown. (Iíve not tried this myself---it might be less trouble to simply find a guaranteed salvaged cluster, vehicle and model year specific.)
Showing the servo shaft, a pointer and range limit stops of the faceplate opening:
Iím not sure the exact reason for these features but may edit this if it becomes known to me at a later date.
So this is inside a working cluster and now shouldnít be a mystery or unknown part of our vehicles. An upcoming project will have me modifying a 97-98 F-Series/Expedition cluster with factory tach to be used in my own Ď00 E250 van. Look for it sometime soon and thanks for reading!