View Full Version : Automotive Circuit Digrams

12-16-2011, 08:43 PM
Would anyone happen to have good links for a fuel injector and ignition coil driver circuits that can interface with a prop? Id imagine you would use a mosfet somewhere.

12-16-2011, 10:32 PM
This may help

12-16-2011, 10:42 PM
Thanks for posting the link to Alldata icepuck.

12-17-2011, 02:14 AM
Alldata provides vehicle manufacturer's factory service documentation and unfortunately this is "dumbed down" for persons who do not understand electronics and barely know electrical wiring.

With that said, the factory service documentation I have seen never shows schematic diagrams of any electronic modules. Rather they just show pin connections and give a general description of how an electronic module works. And they say very little about the operation of engine control computers.

Also as a rule, there are no "data sheets" available for any automotive parts available anywhere (as it is with the rest of the electrical / electronic world). Just part numbers on the box typically!

There is a "home made" (if you will) complete fuel injection system with all the schematic diagrams and software quite well documented. That is the "MegaSquirt" and it can be found here...


12-17-2011, 04:23 AM
A lot of the current injector drivers use IGBT's not MOSFET's
I have not been able to find any of these drivers.(the only numbers look more like date codes)
I read about an IGBT injector driver TO220 device in a Nuts&Volts mag. back in the day...But I can't seem to find it now.
This device pulsed-out a short full current pulse..To lift the injector off seat...Then cut current to just hold the injector open for the pulse duration...This was done to keep from over heating the coil in the injector.
The pulse looked similar to this jpeg

12-17-2011, 07:17 PM
if it came down to it could I use mosfet or some other switching transister?

12-17-2011, 09:46 PM
I think too MOSFET's would work.
Take a look at this

Jorge P
12-18-2011, 06:33 AM
You can easily get schematics of automotive circuits at your Library's Reference section. Look for the Chilton and Haynes manuals. I have been told by several auto repair enthusiasts that the Haynes manuals are better. Myself, I found that what is left out of one is usually in the other, so I always have both for my vehicle.

Most Libraries I have been to will not let you check out reference materials, so you can just make copies of the electrical diagrams. If you have a school ID, you can get a discount on the printing costs.

12-18-2011, 11:14 AM
I'm afraid I have to correct you.

Haynes books does NOT have the required diagrams. They only have the 'wiring looms' Anything more is considered 'beyond the scope of the book'.
They write the books by tearing down a car and re-assembling it., and don't get any information or help from the manufacturer.
Anything they don't feel competent to do themselves they just skip or tell you to get fixed at the dealer...

The wimps didn't even try to dismantle the ragtop sunroof of my car model(Citroen Berlingo) because 'Removal of the roof first requires the headlining to be removed, which is a tedious operation, and not a task to be undertaken lightly'

The one thing they're 'famous' for is that just about every procedure begins with disconnecting the battery...

12-18-2011, 05:56 PM
Right. The automotive repair books sold at auto parts stores cover many models and many years and have very few pages of wiring diagrams for a particular vehicle.

However the manufacturer's factory service manuals are typically 2000 pages of information and 4 phone sized books to a set. And just on one specific vehicle! For example I have a factory wiring diagrams book for my car which is JUST wiring diagrams and over 100 pages in itself. However it does not show schematic diagrams of electronic modules, just the connections to those modules and what each pin is for.

You can order factory service manual sets from a dealer or from alldata.com (about $160 for complete set of 4 books). Or can view the information online at alldatadiy.com

12-19-2011, 12:01 PM
There's a TON of good info on fuell injection for DIY guys here http://www.megasquirt.info/ Including detailed schematics and methods for injector controls

12-20-2011, 12:50 AM
For a MOSFET circuit, look at the Megasquirt schematic. It used a MOSFET driver to control 2 channels. If you wanted a simple, cheap circuit, use a TIP120, a 10k resistor, and a 1N4003 clamping diode. This is what they used in the 80's for driving injectors. Ignition coils are typically driven with an ignition module because there is either a hall effect, VRS, or optical interrupter pickup for the ignition timing. GM uses VRS, Ford uses hall effect. These modules are generally easy to drive with a 2N2222 and a pullup resistor to 12v. A 4.7k to 10k resistor would be fine for the base, a 1k pullup would probably work. The GM 5 pin HEI module is the easiest to interface to and use as a plain old coil driver.