when I jump E1 and T1 to check timing on my truck it doesn't change anything.. It runs ok but the strange thing is my timing mark on pulley is showing up about 12:00 oclock, straight up, while the timing marks on the block are down around 2:00 ..if I retard timing with distributor as far as it will go it is still showing on timing light at better than 25+ degrees and the engine wont hardly pick up any RPM's. I tried moving a tooth on the distributor and the lowest the degress would read was about 21 degrees. Then the motor was so retarded it would hardly run. I moved the distributor back to where it was and got timing mark showing at 12:00 oclock again. I have seen that the TPS may be the issue but when I disconnected the TPS it didn't seem to even affect how the motor reved up. should I disconnect the TPS than see if the jumper works or what? Any idea how the TPS affects the timing jumper? i have seen a post saying to check ohms between E2 and idl , are these pins on the TPS itself or in the diagnostic jumper box for the timing jumper? here is a picture of where i am looking.

 

I had a similar issue with my 94, all I can tell you is swapping the tps fixed it instantly. After the change I read 10 btdc and the truck ran great.

 

I've spent a day trying to get the TPS off. Bottom screw not budging. Hard to believe Toyota didn't use allen heads for these. By checking voltage and ohms it appears to function correctly but i dont know about anything but the ohms and voltage on the 5 volt wires. There is also a 12 volt and one below that . It may be as simple as adjusting TPS or as you say replacing it. I still have to check to see if the pulley slipped on the rubber bushing. But I dont think that would affect the base timing jumper not working.

 

I recently pulled the heads off mine so broke both those screws loose whiile the plenum was off, just in case I wanted to replace the tps later, which I did. The truck did run fine prior to the tps swap, I just couldn’t get the timing set. However, after swapping the tps it ran and idled like new. Is your tps original to the truck? To be honest, I don’t waste much time testing 25 year old sensors, if they are suspect I just replace them. I posted a thread about my deal recently, did you read through that? Honestly, if I were you I’d just pull the throttle body. Easier in the long run.