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I printed out the wiring diagram for 1227747 ecu but i am confused on what pins get constant voltage and what gets switched. The injectors get switched. The fuel pump relay is switched. Does the ecu send out power to apply the fuel pump relay? I believe pins b1 and c16 have constant 12v. Basically i just need to know what pins get power and when. Sorry for my noobishness. On the plus side i have the fuseblock relays and wiring harness in the truck.
So the esc and injectors and pin a6 i have tied together with switched 12v on crank and on. B1 and c16 always get power tied together. The coil gets 12vswitched with crank and on. The coil sends 12v to distributor through the 2 wire connector .
So i think i have the power wires down. Next question is regarding the grounds. Some wires seem to get grounded to the ecu and some to the engine. But then some say chassis ground. Can i just ground all necessary things to ecm and the rest to the engine block. I read that its best to ground all things in one spot. Thanks
Nothing get's grounded to ECM. There are wires from ECM to ground and the ECM uses these to ground a circuit to turn it on, like injectors have power coming into them and the ECM uses a ground to complete the circuit.. or fire the injector if you will.
There should be two sets of ground wires, one is diret grounds for ECM to use and the other is grounds for sensors etc... system grounds and sensor grounds... it just takes a little time to go over wiring diagram and tackle them one wire at a time. Yes several wires can end up on same ground. Stock there are two ground circuits and they both end up on intake manifold bolts.
IIRC B1 and C16 get constnt power all the time. A1 does not! When key is turned on A1 puts out power to fuel pump relay to turn it on. Don't forget B2 that ties into the power going to pump, it comes back to ECM to let it know fuel pump is running.
A6 and the coil need to get power when key is on, all the way to crank and back to key on uninterrupted!
a12 goes to engine ground and can be tied to d1.
a11 and 12 are solder connected in ecu so use them both as grounds.
a11 says map sensor ground. so does the map ground go to engine or a11?
d2 sensor ground goes to engine block
I think thats it d14 and d16 go to ground out the injectors to pulse them.
school starts for me in one week and i am stressing a little with this tbi thing. I really want/need this done before then. thanks for your help eagle mark on this post and others.
HTH! :rockon:Quote:
Originally Posted by joegreen
ok so i plugged in the computer for the first time today. turned the key and a second or 2 later heard the fuel pump relay click. i checked the voltage at the tan with white stripe wire coming out of the relay for 12v. it registered that it was a ground. so my question is it the tan wire supposed to give out 12v or activate a ground and ground the fuel pump. Also i checked my 5v references from the grey wire and they read 4.9 which is all good. it feels good to see it finally do something.
When you turn the key on the fuel pump relay will energize for 2 seconds and turn off. Then when you go to crank it will turn back on and stay on as long as engine starts!
A1 Green/White turns on relay. B2 Tan/White is tied into power to fuel pump from relay to let the ECM know fuel pump is running. This wire can also be Gray going from relay to fuel pump and the tied wire to B2. Both are power wires, I'm not sure what they do when relay is not commanded to be on.
Sounds like your doing OK! :thumbsup:
great thanks. Its a learning process
Ok so i started the truck today. It seems to run ok when cold but when it warms up the throttle lags. Like when you accelerate it bogs and backfires out drivers side.port. I checked out the tps voltage and ohm tested the cts and both checked out fine. I do not have the o2 sensor hooked up yet or the knock sensor or vss. I need my truck for monday and need things to troubleshoot. Whenits cold it responds fast. Both injectors are brand new and put out a nice stream when accelerating so it leads me to think timing issue. I set timing to 0° when i put in the distributor with the 1st cylinder piston at tdc on compression stroke.
You really need to get everything hooked up, at a minimum the O2. Sounds like the timing should be close enough to get it going.
I know but i need to be able to drive to my friends house so i can weld in the o2 bung
ok so i took it for a test drive today and i barely got down my road and back because it kept coughing and stalling. anyway i rented a fuel pressure tester from autozone and set my fuel pressure to 13 psi it was at 11psi. i modified the regulator so it is adjustable. next i took my timing light and set timing with the engine running. to my amazement it was 8* atdc so i brought it back to zero with the wire unplugged. i thought it would be right at zero after i set it manually but this is why i double check things. anyway it ran pretty good afterwards. i do have a stumble when you first take off from a stop but other than that perfect. so far i have the tps, map, knock, vss, esc, cts, distributor, coil but i do not have the o2 hooked up yet. i received my bung in the mail so tomorrow i am going to drill a hole and weld it in. i am pretty happy so far. it is definitely different than a carb as far as gas pedal modulation goes. thanks for everybodys help.