Ok on my 87rx7 TII just finished a rebuild runs well except its very hard to start in cold weather... read about how the waterthermosensor might be causing this so I replaced it... realized the plug socket was actually the culprit so I cut it off and hooked 2 male connectors to the cut wires (wraped one with electrial tape) connected them to each side of the sensor...but I just guessed... now the car wont start at all....
dosent catch or sputter just cranks away.... tried resetting ecu.. nothing...

one thing that does happen that didn't before is the fan behind the radiator starts up as soon as I turn the key to the "on " position..... also the battery seems to die much quicker then usual now (just had it tested and they said its still like new.... only 2 years old..)

could I have grounded the cables or something by connecting the sensor wires backwards or does it even matter which plug goes where?

 

The fan is a clue that the ECU is seeing a hot engine signal.

To find a rogue battery load.
Remove the battery ground & jumper in a small 12v light.
It will light if there is a load somewhere.
Isolate systems by pulling fuses until the load drops.

 

So you have an electric fan? That could be the draw on your battery, if your alternator is dying.

 

i didnt think the fan in front of the rad was electric but I guess it is...

so what fuses do I pull?

 

just realized the connector on top of the coolent filler neck was disconnected causing the e-fan to come on...

the car now starts but it has the same prob as before... hard starting...

are 3 short flashes then a long pause the waterthermo right?... replaced it already and have been messing with it for the last 5 days and the same 3 flashes always come up.!!!

 

Yes. Follow the instructions on page 4B-25 of the FSM.

 

How do you test the continuity between the waterthermosensor and the control unit?

 

get a good multi meter, one with really long test leads. dis connect the waterthermo sensor, find out which pins the wires lead to on the control unit, remove that connector as well, switch your multi meter to ohms, then test the wires. make sure youre testing the same wire on each end though. you should get a low resistance reading, if the resistance is jumping around or greater than what it should be, then you have a bad or cut wire.

 

So if it turns out I have a bad or cut wire how do I go about replacing it?

 

IF I read this right....the car does not even want to catch/ignite/start. Right?? And now, but not before, the aux fan starts running just by turning the key to ON. Right? Right. So the problem is a blown fuse (doubters need but to look at your Aux Fan Schematic to see why the fan runs with the blown fuse).

Go to your fuse box. Check the third row from the bottom. The third fuse over from your left on that third row. Also check the second fuse over from your left while there. That second one over is the ENGINE FUSE. The third over has control over the Fan. If that fuse is blown, the Electrical Fan Relay relaxes and a circuit is made to the Cooling Fan Control Unit, making it think the fan should be turned ON when it should not be turned on.

A busted Water Thermo Sensor should result in the ECU defaulting to somewhere around 175 degrees (memory, I might have fudged the figure).

If you go to your ECU, pull the middle plug off. Put the digital meters neg lead on a good ground. Put the positive lead on the pin 2I (green wire with a white stripe GW). The meter should read b/t 2 and 3 K ohms if the engine is cold. If the engine is warmed up you should see around .320K ohms.

Or just back probe the green/white wire with the plug connected up and read volts. The voltage should be around .5volts when fully heated up, give or take .1volts

Broken wire......thats why they sell wire at the autostore along with butt splices......or a combination of butt splices combined with a plug clipped off a wrecked car at the wreckyard. Leave several inches of wire if clipping one off at the wreckyard.

There's other methods of fixing the wiring at the plug.

 

the reason the fan was comming on was cause I left off the connector on top of the coolent filler pipe so the car thought it was hot...

I was just wondering about how I run a wire back to the ecu from the waterthermo... I cant really shove it back through the harness.... and I dont know if its safe to run a wire out across the engine.
But the big thing is how do I connect it to the plug on the ECU?

 

[
But the big thing is how do I connect it to the plug on the ECU? [/B][/QUOTE]

You could leave the original wire in the connector at the ECU and then cut THAT wire several inches from the ECU and then butt splice that cut wire to the new wire.

Or instead of a butt splice you could solder the two ends together and cover the results with shrink tubing.

Or you could depin the original wire from the ECU and solder the new wire to the original socket on the end of the original wire. You'd have to cut the socket off the original wire and be careful not to damage the socket.

Or you could cutoff the original wire from the ECU and dead end that wire. Then get a single strand wire to run from the sensor to the ECU. A small gauge, single strand wire can be soldered to the original socket and there will still be enough room to reinstall the original socket with the two wires (one wire being the original old one that is now dead ended an inch or so from the

 

alright ive tried for the last 1/2 hour to test the socket on the ECU but every connector I tried showed 0...

am I not supposed to set it up to ohms?
I've tried setting it up on 1.5, then 6 then 9 v's but the thing didnt move...

what am I doing wrong now?

 

bump

 

for a continuity check start at your highest setting and work your way down. if you are still getting zero just check something that you know works

 

I've checked the entire plug and it all comes up at 0v..
I've also tried every single setting on the meter but nothing comes up...

the car wouldnt run if that was the case so i know im doing somthing wrong....

 

I lost track of what you are doing. Are you checking the water thermo sensor out from the ECU plug???? Or running a new wire to the ECU plug???

If trying to read the output from the ECU, you need to leave the connector connected to the ECU and back probe each individual pin in the ECU. To know what each individual pin should read (on the whole), you need a pin out from the FSM. On a series four, pin 2I is for the water thermo sensor. A green wire with a white stripe.
https://www.rx7club.com/forum/attach...&postid=488871 ECUPINSONE
https://www.rx7club.com/forum/attach...&postid=488875 ECUPINSTWO
https://www.rx7club.com/forum/attach...&postid=488879

 

There are five pins different on a series four turbo vs the series four non turbo pinouts from above. Pins 1C1R, 1S,2K,3D. Other than those the rest are the same.

 

see I didnt realize i needed to "backpin" when testing it.. i thought I could test it with teh connector unplugged!

thanks a lot HAILERS!

 

alright i finally found a day off when I could get back to my car...
I tried before testing the ecu connector and i found out I was doing it wrong by disconnecting the plug from the ecu....

Now i've tried for the last 1/2 hour to test the waterthermosensor pin 2I along with other pins and every test I do still comes up at 0v...

If the voltage is supposed to be between 0-2 (estimating) for pin 2I should I not set the voltmeter to 1.5 or above volts and it should show a reading?

I've tried backpinning each pin but I am a little cautious of shoving the needle way into the plug, I dont want to mess up a good pin if I dont have to...

how far should I shove the tester needle into the back of the pin? Its about 3/4" long and its been at least 1/4" in each time.. and yes i've stuck it in further as well with no luck....

p.s I have the key in the ON position....
p.s.s. if the battery was low does that make a difference?... its only down to 11.6

 

bump

 

bump again

 

nobody have an idea whats wrong?

 

I have also had the car idle while testing the ecu and still nothing shows up on the voltmeter... all i want to do is know which wire from the waterthermo goes where... I need to splice in a new plug and I dont want to do it backwards....I'm also wondering if need to run a new wire instead!

 

Connect all the plugs to the ECU. Put your digiatl multimenters negative lead on a good ground such as one of the studs that attach the ECU to the bracket.

You'll need a piece of wire to shove into the back of the connector where the green/white wire is goes into the middle plug. I sometimes use a piece of single strand twenty gauge insulated wire, bare at both ends. Shove one end into the plug alongside the green/white wire. Put you positive lead on the other end of that single strand piece of wire. Don't let either end of the wire touch ground.

With the engine running and hot the meter should read about .5volts. If cold it could read a couple of volts. I don't remember right now how high.

If you read nothing there........put that piece of wire in the back of the small ECU plug, at pin 3E, 3H, 3E or 3F. Each of those should have approx 12v or battery voltage.

If those pins show nothing with the key to ON.....then its a meter problem????? Or user problem???? Try the meter on the battery and see if it is working.

Or if your a bit worried about toasting something.....put the meter on ohms. Put the neg lead on pin 2C.

Pull the middle plug off and put the positive lead on the green/white wire (pin 2I). You should see resistance IF the wiring is good b/t the sensor and the ECU plug