UnintegratedCircuit
Part 4 - Removal & Opening
Removing
Removal of the TPS is relatively straightforward - it is held in place by two 3mm hex/Allen screws, thus a 3mm hex screwdriver/bit or a 3mm Allen key will be required. Before proceeding, it may be wise to make a mark of the current TPS adjustment to aid the reinstallation process. The first screw is easy to find as it is located on the outside of the TPS, away from the engine and towards the front fender. The second screw, whilst not difficult to locate, is more difficult to remove and replace. It is located on the opposite side from the first and is thus covered by the TPS module itself. Take care not to drop the second screw when removing - stick a spare hand underneath the screw for the final few threads, looping underneath the throttle body from the front-facing side of it if necessary.
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Once the screws are removed and safely stored (i.e. in a glass or similar), one can remove the connector by depressing the metal wire latch and pulling the connector away from the TPS module. A gentle wiggling motion may help with the removal of the connector, although too much violence here could bend or snap the male metal contacts on the TPS module.
Opening The TPS Module
A quick warning: it may be handy to have some paper towel to hand as my TPS (before opening) appeared to be full of engine oil. It appeared this was seeping into the module via the shaft that connects it to the throttle plate. If time is not of the essence, it may be worth leaving it on some paper towel overnight to allow the oil to drain somewhat, although this is not mandatory. Similarly, be prepared for the fact that oil may start leaking out of it if attempting this in an indoor environment.
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Whilst the TPS module does have plastic 'tabs' visible around the side, it is actually glued together rather than being clipped. This does make opening the module a somewhat one-way affair, but it could easily be glued back together using superglue once inspection and/or remedial work is completed.
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The approach I took to open the module was to insert a flathead screwdriver into the 'seam' where the plastic tabs were visible. After chiseling out a small 'foothold' for the screwdriver, the screwdriver was used to pry the two halves of the case apart from one another. In hindsight, it may be worth employing a little more patience and beginning with running a scalpel blade along the seam. Do not be afraid to use generous force during this step - the case plastic was more 'soft and chewy' than brittle, so the likelihood of snapping the case is quite low (although it may deform a little around the pry points).
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Once the case is in two halves, the inside of the TPS module should look a bit like Figure 1 below.
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Figure 1 was taken after the repair process; however, this is very similar to how the inside of the module looked when first opened up. Thorough blotting of the inside was carried out to remove as much engine oil as possible. Some carb cleaner was also sprayed to help speed up the process and enhance the clean, although electrical contact cleaner is probably a better recommendation if it is to hand. Another good cleaner for electronics is isopropyl alcohol (rubbing alcohol, IPA, etc.).
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The (once upon a time, at least) grey microswitch on the right-hand side of the module is the idle TPS, and the copper strips on the left are the wide-open TPS. Looking closely, around the area of the right-most hole in the central 'cam', a small lobe can be seen. When the throttle is fully opened, the lobe rotates around with the throttle plate and presses the two copper strips together.
Reinstallation
Reinstallation of the module can be completed as the reverse of the removal process.
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With regards to sealing the unit back up again, as mentioned earlier, superglue could be used to seal both halves of the case back to a good approximation of the factory state. If doing this though, make absolutely certain that the issue has been rectified following the steps in Sections 5 & 6.
My short-term method (rapidly progressing into the medium-term) was simply to tape the two halves of the case back together using standard black electrical tape; four short strips were used, again at the locations of the aforementioned 'tabs'. This method allows one to re-open the case easily enough if the fix failed; however, it keeps the case together whilst reinstalling back into the vehicle and proceeding with a proper final test.
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When reinstalling the two hex screws, my personal preference was to install the easy-to-access screw first, tighten it down a little, and then install the 'blind' screw, again taking great care not to drop it. Both screws can be started by hand, and it is often beneficial to turn the screws anticlockwise until feeling them 'drop' into the threads as this helps prevent cross-threading screws.
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