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Electrical issue? No speedometer, underpowered, throttle.


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Been fighting with my wd21 for a few weeks now. Speedometer has been intermittently not working but was not affecting driveability until this week. Suddenly the other morning the vehicle began running very poorly once it heated up. Extremely loud emission, underpowered (couldn't even get up small hills) , and throttle was all over the place in that you had to adjust it to get right mix I believe or it just made a chunk noise. ( I did recently installed a new thermometer and radiator which is what got it back on the road. This same noise was made once the engine heated up, but since replacing has run well until this week.)


I went home and read the codes and the eccu showed vehicle speed sensor and exhaust gas temperature sensor (only on California equipped emissions) I fixed the exhaust gas temp sensor by sodering a wire and cleaning it up. Believe it was gunked up from hanging below the dipstick for checking oil. I have a parts truck and removed the vss sensor from that and replaced. When I reconnected the battery after replacing vss, the doors to the truck locked which I found odd. Drove the truck and while the shifting improved and timed better, I am still underpowered, and the speedometer display is still not working. I believe it may be electronic because intermittently last week the display would come back and truck drove like a dream. When speedometer stopped working again it would return to chunky throttle and underpowered. Thinking maybe a short or bad ground? Any advice on where to start looking or what it could be would be greatly appreciated


I've got the fsm, and Chilton and Haynes book and am going to check the rest of the emissions system today and see if I can find any issues there. Will also read codes and see if vss code is still thrown.

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I will pretty much guarantee you have a ground issue. 90% of the electrical problems I've found with this frame have to do with ground problems.


What codes are being thrown from the ECM, and do the other guages still work on the instrument panel?



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Thanks for the reply. Gas, temp, and tach work speedometer is only issue. As I mentioned I replaced the v.s.s. because I'm lucky enough to have a parts truck across the lake from where I live. Same year, engine, and trans but does not have the California emissions. I did start cleaning grounds as I run into them because I believe that is the vss issue as well...


I ran the codes today and the 35 cleared and is now replaced with code 32... the e.g.r. system. I tested the diaphragm as described in the manual and it passed the first part for when engine was cold, but I couldn't get it to work for the second test. The truck does seem to run better cold so believe the part could be not functioning. I started trying to remove the e.g.r. from parts truck but am having issues with getting it off. Stopped for the day before I broke something. Also still throwing code 14 the v.s.s. but I replaced that and believe it to be in working order because shifting has improved considerably and a light that used to come on sporadicly when driving at night due to read door latch came back after replacing the sensor.


Have tested other portions of the emissions system piece by piece and so far have fixed the exhaust gas temperature sensor, replaced the carbon canister because it failed the described test, and put in a new pvc valve because my buddy had a new one and it was simple.

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On your egr valve you will see what looks like a second little round valve... Do you see a small 1-2" long hose connecting 2 metal hoses? Mine had a split in it and was causing the code 32.


Looks like this:



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When in doubt, go through the ENTIRE troubleshooting procedure listed in the FSM.


If you've gone through the testing of the specific valve, then make sure that you check the wiring associated with the troubleshooting procedure.


I'm attaching the sections from the FSM in the event that others may have these issues as well.









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Awesome information thank you. Cleaned egcr valve and replaced some hose and cleared that code... throttle is better. Still having issues with electronics pertaining to speedometer and believe I'm having ground issues or a short. Any direction in sourcing that ground or test the circuit containing the v.s.s and similar connectors on trans? I've got the fsm but have difficulty following diagrams..

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