Troubleshooting 7730 injector driver.
08-14-2017, 09:00 PM
#1
Troubleshooting 7730 injector driver.
I'm doing some troubleshooting on a 7730 based car. I've got a VATS simulator module feeding the 30Hz signal into the F10, C3 dark blue wire, and I have no injector pulse. Engine will fire on starter fluid.
I've got +12v to the injectors. And I have fuel pressure. The thing that I'm not sure about is I'm also seeing +12v on the dark blue and dark green injector driver circuits. Should these be +12v when they aren't being grounded by the driver? I'm getting no ground pulse when cranking it over. Could the injector drivers be shorted to power inside the ECM or is this normal when the driver is turned off?
I found another similar thread when searching and ultimately his ECM was bad.
GD
I've got +12v to the injectors. And I have fuel pressure. The thing that I'm not sure about is I'm also seeing +12v on the dark blue and dark green injector driver circuits. Should these be +12v when they aren't being grounded by the driver? I'm getting no ground pulse when cranking it over. Could the injector drivers be shorted to power inside the ECM or is this normal when the driver is turned off?
I found another similar thread when searching and ultimately his ECM was bad.
GD
08-14-2017, 11:32 PM
#2
Re: Troubleshooting 7730 injector driver.
Seems that this is normal. The driver circuit on my 7165 ECM also has +12v on the injector ground control when it is not active.
Back to the VATS drawing board. I've tried giving it both 30Hz and 50Hz signals and it doesn't want to fire the injectors.
GD
Back to the VATS drawing board. I've tried giving it both 30Hz and 50Hz signals and it doesn't want to fire the injectors.
GD
08-15-2017, 12:08 AM
#3
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Re: Troubleshooting 7730 injector driver.
even with VATS preventing the motor from running, it should still start for 1~2 seconds & then die.
do you still have the factory injectors? check the resistance of each of the injectors.
you will see voltage on the ECM side of the injector plug if any one of the injectors are plugged in.
try a noid light and see if it flashes while cranking.
do you still have the factory injectors? check the resistance of each of the injectors.
you will see voltage on the ECM side of the injector plug if any one of the injectors are plugged in.
try a noid light and see if it flashes while cranking.
08-15-2017, 12:29 AM
#4
Re: Troubleshooting 7730 injector driver.
Ah of course! I hadn't unplugged them all. So I'm reading voltage through the other injector coils. Doh!
You get used to the new stuff where each injector has its own driver.....
I'll check for pulse again tomorrow. Can't hurt to double check. I had no pulse on the control side with my (LED) test light.
GD
You get used to the new stuff where each injector has its own driver.....
I'll check for pulse again tomorrow. Can't hurt to double check. I had no pulse on the control side with my (LED) test light.
GD
Last edited by GeneralDisorder; 08-15-2017 at 12:34 AM.
08-17-2017, 05:48 AM
#5
Re: Troubleshooting 7730 injector driver.
An LED may not have sufficiently low resistance to pull down (bias) the collector of the switching transistor used as an injector driver. Polarity of the LED will also affect whether the output transistor can switch any current or not.
08-17-2017, 11:02 PM
#6
Re: Troubleshooting 7730 injector driver.
Well.... I learned what an (incandescent) noid light does when VATS is in play.
The ECM still pulses the injectors but when it's not getting a good VATS signal it's a high resistance on the ground control circuit so the light will flash but very dimly.
Found it was throwing a code 46. Had one of those eBay VATS simulators pushing a 30Hz signal to the ECM. Obviously it wasn't clean enough or the right frequency or something. I burned a non VATS chip and now I get a normal noid light pulse.
GD
The ECM still pulses the injectors but when it's not getting a good VATS signal it's a high resistance on the ground control circuit so the light will flash but very dimly.
Found it was throwing a code 46. Had one of those eBay VATS simulators pushing a 30Hz signal to the ECM. Obviously it wasn't clean enough or the right frequency or something. I burned a non VATS chip and now I get a normal noid light pulse.
GD