Speedo drive

The speedo has stopped working on my Hiace. It has an electronic 3 wire drive which, when i attempt to remove it for testing, allows oil to come out.
Where do i fill this end of the transmission, which i assume is the overdrive?
It seems to be getting 12 volts and ground-Can i test the speedo drive without removing it? maybe by chocking up the rear wheels and putting it in drive. any pointers would be much appreciated!
thanks
Mark

Welcome, I note your questions but there is a total lack of data and context so I'm unable to suggest anything. Perhaps you may want to post some useful data:

What year is your hiace?

If it's electronic why do you have oil coming out? There should be no oil in the dashboard.
Where exactly is this oil?
Why are you needing to fill a transmission?
Is your Hiace manual or automatic?

If you have a function generator you can simulate speedo pulses and see if the speedo itself works on the dash, but only if it's an all electronic one (but those have no oil!) I'd try 100Hz through a 100 ohm resistor of about 10V first.

Thanks, excellent suggestions.
i apologise for not giving more information initially. i wrote the post in a bit of a rush and fluster!
first off, i haven't done anything on the dashboard other than a visual inspection. everything i am referring to here pertains to the underside of the vehicle.
The van is an LH119 cruising cabin with selectable 4wd with hi/lo ratio, auto box and the 3l, 2.8 diesel engine. The speedo drive to which i, correctly or otherwise, refer to is a small worm(?) drive connected to the output shaft on the transmission. it has 3 wires, 12v, ground and signal wire.
i can measure 12v and ground on the cable from the dashboard, and was attempting to remove the small component (speedo sender?) to measure it on the bench. its held into the rear of the transmission by a 12mm bolt and can be pulled out once this bolt has been removed. however, on doing this oil starts pouring out of the hole, which is why i wanted to find out how to top this up. i assume the last part in this transmission is the overdrive? can't see a filler plug anywhere, though there must be one!
i think this diagram might shed some light on things
https://www.megazip.net/zapchasti-dlya-avtomobilej/toyota/hiace-38414/lh119-54731/lh119v-rrpes-909890/speedometer-driven-gear-atm-17719038#/il-410979619-4448125-4448125
I don't have a function generator-maybe its something i can cobble together? or perhaps you can suggest a way of sending a pulse to the dash. Another problem I'm having is in finding a relevant wiring diagram so i can check the continuity, so any assistance in this regard would be most appreciated.

Ah I see, you pulled out the sender.

1. What year was your Hiace made?
2. Is it manual or automatic?

You may want to add this information to your sig or avatar.

Hi Fritzy,

1. Did you completely remove the Speedo Sensor Assy from the Transmission Housing??

2. If so did you check the Speedo Drive Gear on the Sensor to see if it was stripped??

3. If it has a separate plastic drive gear on the Transmission Output Shaft it could also be stripped, have you checked to see if the Speedo Drive Gear in the Transmission is still in it's proper place or stripped??

4. If the Output Shaft Speedo Drive Gear moves out of position it won't engage the Sensor Drive Gear if a new sensor is fitted.

5. If the Drive Gear on the Transmission Output Shaft is part of the Shaft itself then that won't be an issue.

6. If the Sensor Drive Shaft seizes it can cause the gear teeth to strip which in turn can cause the output shaft drive gear to move.

7. Assuming you haven't taken the Sensor Assy completely out of the Transmission you can remove the actual sensor part of the Speed Sensor Assy. (The Black Plastic part attached with the 3 Phillips Head Screws) but before doing that check the Connector Terminals.

8. Disconnect the Wiring Plug and have a close look inside to check that none of the Terminals have backed out of the Plug. If they have then that could be your problem. To fix it pull back the rubber insulating boot and remove some of the insulation tape to reveal the wiring. Push the terminal back in and check it is secure, a slight pull on each wire will establish that. If it keeps pulling out check the tang on the terminal is not damaged. A simple adjustment of the tang can fix it. Sometimes it can be as simple as that to fix the problem. A quick reconnect of the plug and drive the rear wheels to check. If it works, problem solved. Re-insulate the wiring, let the car down and off you go. If that's not the problem go to next step.

9. Assuming you have already established that the Sensor is getting a proper Ground and full 12V to the Terminal check for a Pulse Signal with the Sensor Assy still insitu and the Plug connected, get 2 x Modified Paperclips. insert one into the rear of the plug into the 'SIGNAL' Terminal and one into the 'GROUND' Terminal. Ensuring they don't touch each other by bending them away. Connect some Long test leads (1 x Red, 1 x Black) with Alligator Clips to the appropriate Paperclips and then the Multimeter probes accordingly. RED Probe to 'SIGNAL' Lead and BLACK Probe to 'GROUND' Lead. Turn the Multimeter on and select 20V+ setting.

10. Start the engine and put in gear. Slowly allow the wheels to rotate. While sitting in the cabin check the Multimeter (Hence the Long Test Leads). It should pulse a Voltage reading between 0V and 12V. If it doesn't the Speedo Sensor is faulty or your testing wires have fallen out. If you have a sidekick they could lay underneath and make sure they are connected.

11. If you're getting a Pulse then it's time to check the signal at the Instrument Panel as there is no point removing the Sensor Assy as that is not the issue. Go to Step 15.

12. If you're not getting a Pulse Signal check the physical aspects of the Speedo Sensor Assy.

13. You can do this by removing the Plastic Sensor Part by undoing the 3 Phillips Head Screws. It should reveal the Sensor Drive Shaft.
Now just drive the wheels and see if the shaft is turning. If so that will eliminate any seizure or gear stripping issue. If it doesn't move then you have problems and no choice but to remove the whole Sensor Assy.

14. If it is turning then you can check the Sensor Part by using a screwdriver bit or something suitable in a drill to turn the sensor wheel inside the Plastic Sensor part in the same direction the shaft would. Test it by using the procedure in Step 9. NO Pulse Signal then the Sensor is faulty. Replace the whole Speedo Sensor Assy or just swap out the Plastic Part from a replacement part. Saves removing the Mechanical Part of the Assy and making a mess.

15. Assuming a Pulse Signal go to testing at the Instrument Panel. You should be getting a Pulse Signal at the Speedometer 'IN SIGNAL' Terminal Point.

16. If not start checking for continuity from Speedo Sensor Plug to Instrument Panel Plug and from Flexible Circuit Board to Speedometer.

17. You can trace the Speedo Circuit on the Flexible Circuit Board by backtracking from the Speedometer 'IN SIGNAL' Terminal to Wiring Connector. That will also Identify the correct Speedo 'SIGNAL' Wire for Continuity Testing.

18. NO Continuity to Instrument Panel then you need to locate the Open Circuit in the wiring harness. NO Continuity from Wiring Connector to Speedometer then assume Flexible Circuit Board is faulty or wrong 'SIGNAL' wire selected. A separate "OUT SIGNAL' wire should return to the ECU. Make sure correct wire is tested.

19. Assuming the Speedometer is held in to the Instrument Panel by 4 Small Phillips Head Screws, which also attach to the Flexible Circuit Board Terminal Points, and you have a Pulse Signal at the Speedometer 'IN SIGNAL' Terminal Point on the Flexible Circuit Board then you have to assume there is NO power to the Speedometer '12V' Terminal Point or it's not Grounding at the 'GROUND' Terminal Point if the Speedometer is not Physically working. Further testing will be required on the appropriate circuits. If power to Speedometer '12V' Terminal Point and Grounding is OK then assume the Speedometer Assy itself is Faulty.

20. These kind of Speedometers have a Smaller Circuit Board attached which regulates the Voltage to the Speedo Motor that turns the Needle Gear to move the Needle to the appropriate Speed. This also sends the Speedo 'OUT SIGNAL' to the ECU for the Engine Management System to operate optimally. This is usually what fails. It is part of the Speedometer Assy and cant be replaced separately. You'll probably find that the 'Check Engine' Light will be illuminated as well. If it is on the EMS will go into Default Mode and the Engine Performance will suffer. This is why running a vehicle with a Speedo disconnected can affect performance. After repairs the Check Engine Code can be cleared by disconnecting the battery for 30 Seconds.

Sounds like a lot of fucking around but it saves replacing unnecessary expensive parts.

Good Luck in your endeavours

Cheers
Geoff

Good advice.
Sorry I didn't spot 'auto box' in the middle of your reply fritzy until I re-read it just now - my bad.

To check the oil level in an auto-box you find and then pull the dipstick. This is right at the back of the engine bay under the passenger seat and you'll need to use a finger to unclip it first.

The stick will say what type of ATF to use, DII means Dexron II.
It will have a cold min/max and a hot min/max.

The min/max are levels while RUNNING at idle on level ground, and top up through the dipstick tube with a good funnel and some ATF in a 1 litre container so you can get the angle. I think you need to push it fully home each time to get the level but am not 100% about this.

If your van is 1996 or earlier you may have a dry electrical joint in the speedo in the dashboard, if so you'll need to pop it out and reflow some solder around the joints of the PCB at the back of it. Use new rosin cored solder and be very fast with a good soldering iron, just a dab is needed.