Trouble Shooting
Start Troubleshooting Here No Start Trouble Codes Car Runs, but Seems to have a Problem ECM Wiring Coil-Module Wiring Fuses Fuel Pressure Test Fan Circuitry Fuel Pump/Fuel Injector Circuitry Torque Converter Lockup
Trouble shooting used to be a relatively simple business. If the car had spark at the plugs and gas in the carburetor, it would usually try to run. If one was missing, it was generally not that difficult to figure out what the problem was.
It ain't that easy most of the time with the fuel injected cars as too many things are interrelated and a flaw anywhere in the system will usually bring things to a halt. To further complicate matters, the wiring harnesses on our cars are 20 years old and connectors may be flaky, corroded, broken, etc. On the other hand, the cars still need fuel and spark to run so if you understand older pre-electronic cars, then it is not that hard to pick these up.
It is very important to work through the problem with some logic rather than changing parts on a hit or miss basis.
In attempt to provide information to a broad audience, I have included trouble shooting trees from the factory manual to resolve no start conditions as well as diagnostic tips for the various trouble codes.
In an effort to cut to the chase, if the car will not start, one needs to determine three things. Before starting your trouble shooting, be sure the battery is charged and the voltage is not dropping too much when the starter is engaged. If the voltage drops enough, the ecm will not allow the car to start even though the engine is turning over.
1) Is the Check Engine (SES) light on? If it is not, then find out why. The CCCI fuse is one of the problems mentioned in the No Start, No SES Light tree, as well as a bad ECM. I have also found that a blown ECM-SOL fuse will turn the light off and prevent the engine from running although this is not mentioned in the troubleshooting tree for no SES light. I don't see why when looking at the diagrams but it cost me an expensive wrecker ride to figure this one out.
2) Does the ignition have spark? Pull a plug out, put the appropriate wire back on it and lay the plug on the valve cover or hold it to a good ground. Crank the engine. Do you see a good blue spark across the gap? To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
3) Check the pressure in the fuel rail after turning on the key for two seconds. Is it close to what you have it set at? (this does not guarantee that you have injector pulse-only that you have fuel at sufficient pressure in the rail if the pressure drops into the 20's, the car may not start due to a lack of pressure)
4) Pull the fuel injector harness off an injector (mash in on the spring clip on the bottom of the connector and lift the connector off the injector). Plug your Noid light into the connector. Crank the engine. Does the light blink steadily while cranking? (this verifies that the injectors are receiving injector pulses from the ECM and the crank and cam sensors are working)
Long ago, Jim Testa posted a "How To" get started in the trouble shooting. It is well worth reading in order to apply some logic to the process.
Below is a short cut derived from Jim's article.
No start - no spark, has injector pulse - Check the ignition module (also check the CCCI and ECM-IGN fuses)
No start - has spark, no injector pulse - Cam Sensor or ECM
No start - no spark or injector pulse - Crank sensor or module
This above is a very good way to cut to the chase and start zeroing in on the problem(s).
Armed with the answers you obtained in the above three steps, go to the "No Start" trees and find your starting point. Do the tests suggested.
If the car runs, but does flaky things.....it is always a good idea to check the various grounds...particularly the ground wires that attach to the rear of the passenger head...yeah, the ones that are a pain to get to. Sometimes they are loose; sometimes a wire is broken, and sometimes, there is corrosion in the connectors. It makes life a lot more easy if they are relocated to a stud on the intake manifold, or using a ground relocation kit from Caspers, moved to the firewall. These cars must have good grounds to run properly.
If you want to successfully work on your car following the information provided, you will need the following equipment at a minimum.
Beyond that, it sure helps to have a factory shop manual from Helms (if you cannot find a paper copy from Helms, get the CD version from Jeremy Woods for alot less money) and a coil /module tester from Caspers. Another useful tool is Casper's Cam sensor tool although your volt meter will serve the same function. Having two cars to swap parts between is an easy way out, but, it may not solve the problem given the age of the wiring we are dealing with.
I don't know
how anyone owns one of these cars without a shop manual. The
electrical section, alone, is worth the price of the CD.
One thing that has saved me many a time is a digital camera. If you are going to redo the brakes, or rebuild an alternator, before you dismantle everything, take a couple of pictures of the assembly. I have a tendency to look at things and say to myself, "I can remember that". A month later when I decide to put it back together, I don't have a clue. A picture is really nice to fall back upon.