James Geiger

i have got a 1990 prelude i bought for 100 dollars found out main relay is bad so fuel pump dont work but have to other issues im wondering if there connected one is my flip lights when i put fuses in for them the both open and close constant and dont stop and the other is i dont have spark i bought this to use for autocross and love this style prelude but dont work on hondas alot this is the second prelude i have owned please help

ol' grouch

I just picked one of these up and really don't know much about the car myself. I have worked on different cars most of my life so it's not like I'm a complete idiot, just an amateur one. The last time I ran into a cycling headlight assembly, it was a relay. The owner just wanted the car to drive so I manually opened them and pulled the fuse. Before you condemn your main relay, check the fuel pump relay. Most car companies use the same number relay for several functions. It's a matter of economics. Find a relay that you know is good. Swap it with the fuel pump relay. I picked up a truck once that the owner was thinking his new fuel pump was going out. He just wanted to be rid of it so I bought it. The pump worked just fine but would sometimes rattle. I swapped the fuel pump relay with the a/c relay (don't use a/c much in January) and the rattle went away. I got a new relay, swapped them back and put the new one in the relay box and not a problem for the 8 years I drove that truck.

As for specific advice on these cars, I haven't figured out how to pull the back seat yet. I'm more concerned with correcting LOTS of poor wiring work so the car doesn't burn to the ground.

1funryd

You guys are on the wrong forum for 3rd gen specific questions. This chassis is not like any other Honda chassis.

I recommend you download the online pdf manual for your trouble shooting.

I have it on my site - www.1funryd.com

motoxxxman

main relay = fuel pump relay. just to clarify

keving733

I have a 1990 Honda Prelude si. I have read some of the threads on the S3 flashing light to determine the problem code. What happened is that I read the code as a 01 and that was supposedly was the Oxygen Sensor. I replaced that and reset the S3 light by pulling the 10a clock fuse under the hood like instructed. This erased the code for about 3 days and it began flashing again. When the light flashes it causes the transmission to malfunction. I think it will not shift above 3 gear and is sluggish. When the code is not flashing it runs great and shifts great. The code is still flashing 1 time and then a 20 second delay and then again. Just one flash. I was wondering if that indicates a 10 or a 1 code. I am not sure if it's a transmission problem either due to the malfunctioning of the trans while the S3 light flashes. about 176000 miles on it and in great shape otherwise and well maintained. Is the paperclip jump thing necessary to get a proper code?

keving733

I have a 1990 Honda Prelude. I have not received any feedback on here as of yet so I will try again. Ok I have found the proper code under the floor mat on the passenger side. I have 7 long flashes which indicates a Throttle Position Sensor. I purchased a TPS from Pro Import Tuners. The were helpful and I purchased a TPS. It was shipped and my mechanic installed the new part. I came to pick up my vehicle and it (shifter)was locked in park (auto trans) So I used the key to free the shifter and drove the vehicle. The vehicle was stuck in 1st gear. I returned the vehicle to the mechanic. He scratched his head and tried to calibrate the TPS as recommended with his volt meter. The reading indicated that with the throttle closed was 4.5V give or take and with it fully open .5 V. Just the opposite of what it is supposed to be. So we re-installed the old TPS and re-calibrated it. It worked as good as it did before but again set off the code light and sent the vehicle into limp mode. But the shift was not locked any longer. The vehicle would at least shift up to 3 rd gear when in limp mode. It runs excellent when not in limp mode when the code has cancelled. So looking at the part it appears that it is a different configuration (similar) but backwards. So I learned from Honda that there are no TPS's for my car and I have to purchase a Throttle body at about 340.00 and it takes about 1 to 2 months to get it from Japan. Does anyone out there have any suggestions? The proper part for the throttle body according to the Honda Dealer is 16400 PK2-X10 but there is no sub part number for the TPS. I need some help here c'mon guys!!!

snobordboy

Sounds like the wiring just needed to be swapped around on the one your mechanic tried. In the case that they couldn't figure that out, I would not have much faith in them.

The other option would be to buy another TPS and install it. The Honda ones are set and calibrated on the TB from the factory, but if you slot the head of the screws they use, they can be removed and replaced, and other hardware installed to avoid using the slotted one again.

keving733

Never thought of switching the wiring. The mech is not a honda pro for sure but a real nice fella and willing to help me and is real reasonable. The problem from honda parts is that they apparently do not sell the TBS for my vehicle. They only sell a TB that you have to order from Japan that could take up to 2 months to get. At least what I an find. The Honda dealer couldn't find it either accept on Amazon. All other options indicated that the part is no longer available. I found a TB at Pic A Part used so maybe that could be an option for 100 bucks. Thanks for your reply. I think I might have him try switching the wiring first.

holmesnmanny

90 honda prelude throttle position sensor | eBay

https://honda-tech.com/forums/honda-...moval-2822004/

^^ Don't forget to calibrate it when you install it. It must be calibrated.

keving733

Thanks for all the advice, going to the mech today and I have printed the threads you have sent and I will be armed with that info. We will be calibrating it the TPS for sure. I really appreciate the help. Hopefully this will take care of the Code 7

holmesnmanny

normally it throws a code when the wiring aspect is bad, not really when the sensor goes bad, but you can use the tps calibration thread to help rewire it correctly

keving733

Switched the wires, reset and re-calibrated and it runs like new and so far no codes. Thanks again

holmesnmanny

1funryd

If it is a code 07 then it is a lock up solenoid issue.
This is all on the online PDF manual that I posted last year on here.

1funryd

7 Blinks =

Fails to shift other than 1st<-->4th
2nd<-->4th, or 2nd<-->3rd gears.
Fails to shift (stuck in 4th gear).

Probable Cause:

- Disconnected shift control soleniond valve connector
- Open or short in shift control soleniond
valve A wire.
- Faulty shift control solenoid valve A.

holmesnmanny

check engine, not tranny code

1funryd

Oh I skipped that and was replying to the original thread owners question.

keving733

OK that fixed it for a few months guys. It started doing it again. I replaced the solenoid, plugs and wires and another new TPS. Still get the 07 Code and puts the vehicle in "limp mode" will not shift from third to fourth. The mech that helped me told me that he didn't need to re-calibrate the TPS because he says it only fits in there one way. It worked for a few days and then started throwing the 07 code again. I try to reset the S3 and as soon as i put it in gear or let it idle the S-3 light starts blinking again. What next? The check engine light does not come on just the S-3

holmesnmanny

i think it's time to swap in another ecu and/or another tcu

keving733

Ok I guess that is what's next. Now I gotta find a decent ecu. See lots of used ones.

motoxxxman

that mechanic is a tool. Find a new mechanic.
Calibrating the TPS is really quite simple, just need a volt-meter and some back-probing pins. You simply put the neg cable on a ground somewhere, and the pos cable on the signal wire for the tps. With ignition on, loosen TPS screws, and rotate the TPS body back and forth until the volt meter shows 0.45v. then tighten the screws, and make sure it still reads 0.45v. That's it, done.

motoxxxman

where are you located? I have a few ecu's and tcu's in perfect condition. you can have one of each for free if you come pick it up. I know, slim chance you're local to me, but worth asking. I'd offer to ship it and have you pay shipping, but I'm not very reliable for shipping stuff mainly because I never know when I'll actually be able to make it to the post office to ship stuff.

keving733

Thanks motoxxxman, I just now read your response. I am from a small town in Oregon. I did however find the solution and you were exactly right. It was the TCU. The car is now running better than ever since I have replaced so many components haha, so I guess even though it was a pain it forced me to get some needed maintenance done. I appreciate your help.