where do i start...no spark or cel

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liftedtoy97

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For the past two weeks I have searched and searched on every website I could find toyota related. I have asked "experts" on justask.com...still nothing. And I know alot of people come on expecting you to pinpoint exactly what is wrong with their car just by what they say, I dont expect that, just any ideas that I haven't tried.

It's an '87 with the 7MGE. It all started when I couldn't get my timing set right it kept jumping all over the place with the TE1 and E1 terminals connected. I finally discovered that I had a few vacuum lines misrouted. Well my battery was too dead too start it so I backed it down my driveway and popped the clutch to start it. Got it pulled in the garage, shut it off, straightened out the lines, and when I tried to start it, nothing.

I quickly narrowed it down to no spark...great. What I have tried so far is a new coil, and a used ignitor from another member on this board(thank you). Neither worked. All my fuses are good, I have double checked them literally 10 times. I have checked the voltage to the B terminal at the check connector, and the +B and +B1 terminals at the computer, all read 12.2-12.6 volts.

I remember when I first tried getting the timing set right, when I had the terminals jumped, the check engine light was flashing(probably a code) but I didn't pay any attention to them at the time. Well since then I have disconnected the battery so any codes that were there are gone.

That brings me to my second problem that has come up. The check engine light will not come on at all now like it is supposed to with the ignition on but not started. I can ground the wire that runs from the light to the computer at the computer and the light will come on, but that's the only way it will come on and even then it doesn't flash anything.

I am completely out of ideas. I am not mechanically challenged, I have torn rebuilt the engine in it and built up other toys, however, diagnosing electrical problems is definitely my weak point. I had a buddy who works in a shop and is somewhat better with electrical look at it with me, nothing there. So any ideas someone might have would be greatly appreciated. Thanks.
 

metaphysico

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Check the ground wires in the engine bay. One is at the rear of engine above exhaust manifold. Also check the ones that are under the intake on the driverside to make sure they are connnected.
 

liftedtoy97

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metaphysico;1208280 said:
Check the ground wires in the engine bay. One is at the rear of engine above exhaust manifold. Also check the ones that are under the intake on the driverside to make sure they are connnected.

all grounds are connected, that was one of the first things I checked
 

liftedtoy97

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jetjock;1208088 said:
Flowchart #1:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=29

This time check everything (including BATT) at the ECU while referencing the measurements to E1. No ground (it comes from the intake manifold), no workie. Got ground? Then the connector or the box itself is bad...


will do. wonder if the no cel is related to the no spark, which pretty much means bad ECU. are ECU's known to just go out just like that? could I have effed it up by popping the clutch to start it when the batt was low? I pulled the ECU out awhile ago looking for any burned resistors or something, didn't see anything.
 

liftedtoy97

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dumbo;1209373 said:
have you checked your fusible links, your cel has two on that on that circuit. does your car run if you bump start it still?

yes i checked the fusible links also, no it won't because the other issue I have is no spark, that's what led to me discovering i had no cel
 

jdub

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liftedtoy97;1209353 said:
will do. wonder if the no cel is related to the no spark, which pretty much means bad ECU. are ECU's known to just go out just like that? could I have effed it up by popping the clutch to start it when the batt was low? I pulled the ECU out awhile ago looking for any burned resistors or something, didn't see anything.


No CEL = no ECU power = no start

A push start will not cause this.

Perhaps a basic, dumb question...have you checked the EFI fuse in the engine bay fuse box?
 

jetjock

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Dumbo: If the lamp lights when grounded the power side has to be good.

John: He wouldn't have power to +B and +B1 unless the EFI fuse was good and the main relay energized. That the main relay is closed also shows the ECU is powered (and alive to some extent) since the on signal for the relay comes from the ECU's processing of the ignition switch input.

Course, all this is assuming he's providing good information. You know how that goes but he seems to know what he's doing....
 

liftedtoy97

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jdub;1209539 said:
No CEL = no ECU power = no start

A push start will not cause this.

Perhaps a basic, dumb question...have you checked the EFI fuse in the engine bay fuse box?

yes, that was in my original post of everything I have gone over and checked
 

liftedtoy97

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jetjock;1209546 said:
Dumbo: If the lamp lights when grounded the power side has to be good.

John: He wouldn't have power to +B and +B1 unless the EFI fuse was good and the main relay energized. That the main relay is closed also shows the ECU is powered (and alive to some extent) since the on signal for the relay comes from the ECU's processing of the ignition switch input.

Course, all this is assuming he's providing good information. You know how that goes but he seems to know what he's doing....

haha thanks, I know what I am doing to an extent with electronics, like I said. I can test the stuff, just not sure what to test when it comes to the ECU and more tricky stuff in my book. this is why I was hoping you would jump in when I wrote my original post, you seem to be the electrical genius from some of your posts I have read in the past.
 

dumbo

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jetjock;1209546 said:
Dumbo: If the lamp lights when grounded the power side has to be good.

true i missed that.

so if he has voltage at 'W' and the wiring is good between 'ECU' and 'E1' doesn't that point at the ecu itself then? or am i missing something else?
 

jdub

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liftedtoy97;1207969 said:
I can ground the wire that runs from the light to the computer at the computer and the light will come on, but that's the only way it will come on and even then it doesn't flash anything.


Ahhh...I missed this statement too :3d_frown:

When you did the above, did you connect the TE1 and E1 terminals on the diagnostic block?

You may have missed JJ's earlier post...the grounds for the ECU connect at the intake manifold. Did you remove them, clean the connectors, and reconnect?
 

jetjock

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Redacted per Title 18 USC Section 798
Of the two problems described (engine won't run and MIL won't illuminate) the MIL is by far the simpler to troubleshoot. Therefore it's the one that should be focused on in the hope the more complicated issue will resolve after the simpler one is fixed.

Of the two MIL problems (won't light with the key on and won't blink in diag mode) not lighting with the key on is the simpler of the two. Therefore that should be the focus because there's a high probability once it lights with the key on it'll work in diag mode. In other words when troubleshooting don't make things more complicated than they are.

All the ECU needs to light the MIL key on is power, ground, good wiring, and a good MIL bulb. BATT has power at all times. The ECU needs this power (called "keep alive") to prevent the loss of data stored in volatile memory. DTCs, idle and fuel trim learned values are examples.

Anyway, when the ignition switch is turned on battery voltage is applied to ECU terminal IGSW. In response ECU terminal M-Rel supplies battery voltage to the coil of the EFI Main Relay. The Main Relay then closes and supplies battery voltage to ECU terminals +B and +B1. Power to +B and + B1 "wakes up" the ECU which then supplies ground to terminal W. If there's +12 on one side of the MIL current will flow to ground through terminal W and the bulb will light. It's as simple as that...
 

liftedtoy97

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jetjock;1209790 said:
Of the two problems described (engine won't run and MIL won't illuminate) the MIL is by far the simpler to troubleshoot. Therefore it's the one that should be focused on in the hope the more complicated issue will resolve after the simpler one is fixed.

Of the two MIL problems (won't light with the key on and won't blink in diag mode) not lighting with the key on is the simpler of the two. Therefore that should be the focus because there's a high probability once it lights with the key on it'll work in diag mode. In other words when troubleshooting don't make things more complicated than they are.

All the ECU needs to light the MIL key on is power, ground, good wiring, and a good MIL bulb. BATT has power at all times. The ECU needs this power (called "keep alive") to prevent the loss of data stored in volatile memory. DTCs, idle and fuel trim learned values are examples.

Anyway, when the ignition switch is turned on battery voltage is applied to ECU terminal IGSW. In response ECU terminal M-Rel supplies battery voltage to the coil of the EFI Main Relay. The Main Relay then closes and supplies battery voltage to ECU terminals +B and +B1. Power to +B and + B1 "wakes up" the ECU which then supplies ground to terminal W. If there's +12 on one side of the MIL current will flow to ground through terminal W and the bulb will light. It's as simple as that...


lol piece of cake
 

liftedtoy97

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jetjock;1209546 said:
Dumbo: If the lamp lights when grounded the power side has to be good.

John: He wouldn't have power to +B and +B1 unless the EFI fuse was good and the main relay energized. That the main relay is closed also shows the ECU is powered (and alive to some extent) since the on signal for the relay comes from the ECU's processing of the ignition switch input.

Course, all this is assuming he's providing good information. You know how that goes but he seems to know what he's doing....

so I ran a ground to the E1 terminal on the ECU and at the check connector and got no light...so according to the TSRM my ECU is screwed right? anyone have one they wanna let go of cheap?:D
 

liftedtoy97

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also, does this sound like he is on to anything?

The computer has to turn the check engine light on it won't do any good to ground the wire to turn it on. This is just a quick way to rule out the bulb and wire to it. Usually the is a ground or power feed problem to the computer to keep the light from coming on. There is one other possibility. If the 5 volt reference signal that goes out to all of the sensors like the MAF and the EFI temp and TPS gets shorted to ground it will shut the computer down. Do you have this 5 volt VC signal coming out of the computer and at each of the sensors? Unplug each of the components and see it the light comes on. I saw a MAF short out one time and do this.
 
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