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Here's what I found :
When cranking: 11.54@TDR, 12.57@MAF, 0.07@Alternator.
Battery cables are tight, battery reads 12.6V. Security light turns off after three seconds after turning key to on. I'm at a loss. 0.01V on accessory and 9V at solenoid when cranked, 1.7V on accessory and 0.14V when cranked for starter.
If you are checking voltage on the “S” terminal at the starter while cranking that’s around a 3 volt “voltage drop” on that circuit..way to much !!...always a good idea to check the ground side of the starting circuit too...connect 12 volt test light to BATTERY NEGATIVE...when cranking the test light SHOULD NOT light if the ground is good !!
First off let’s not worry about the F terminal alternator voltage right now...so with the MAF sensor unplugged and with key ON you are probing the 5 volt ref wire (signal) and you’re reading 12.57...this is the YELLOW wire...you should have 12 volts on the PINK wire..did you check the wrong wire ??...PCM fuse 16 is your ignition supply to the PCM...if you turn the key ON I bet you don’t hear the fuel pump prime...do you ??...IGN1 fuse 45(IP fuse block-next to BCM-hot at all times...this fuse IS for a 98) feeds the PCM fuse through the ignition switch...check IGN1 fuse !!...if fuse good “may” be ignition switch...even with bad ignition switch you’ll see something through the switch !!
I double checked and it was the yellow wire that I checked. The fuel pump doesn't prime, the ignition fuse is good. I guess it's time to check the ignition switch.
I double checked and it was the yellow wire that I checked. The fuel pump doesn't prime, the ignition fuse is good. I guess it's time to check the ignition switch.
NO NO, you shouldn’t be seeing 12 volts on the yellow MAF signal wire...anytime I see high voltage the ground may be “elevated” and in your case the ground is elevated 7 volts !!...check the black/white wire on the MAF...that is a block ground (G106) and NOT a PCM sensor ground where you should read LESS than 100 Mv (.1 volt)...with key ON see if you see 7 volts there ??...if ground is good will have some wiring checks to do !!...see my voltages below !!...ground and the 5 volt ref !!...to check voltage drop across ignition switch connect voltmeter red lead to battery POSITIVE and black lead to one of 2 test points on PCM fuse 16...crank engine and read the “voltage drop” directly...you should not see more than .2 or .3 volts on the voltmeter while cranking !!
Here is the starter schematic that you can use to figure out why your engine will not crank. You must figure out where you are dropping voltage There are TWO sides to the TDR. The CONTROL side that deals with energizing the relay and the LOAD side that allows the higher current battey voltage to switch ON and OFF to the starter SOLENOID.
IF, you have battery voltage on the purple wire that goes to the S terminal on the solenoid, that starter solenoid should be energizing and allowing the starter to crank. Whack the started when someone HOLDS the key in the START position and see if it comes to life.
BC
Last edited by Bill Curlee; May 15, 2019 at 09:31 AM.
If you are seeing 12 volts on the 5 volt ref. MAF wire see what you are reading on the IAT sensor (2 wire sensor closest to the throttle body) on the TAN wire...also a 5 volt reference...that is your IAT signal wire...we have a couple issues going on here !!...also the PURPLE wire on the IAT sensor is a SENSOR ground to the PCM...should be less than .1 volt !!
Voltage over PCM fuse 16 drops from 12V to 0.24 when cranking.
IS THE BATTERY FULLY CHARGED ??...Are you measuring battery voltage then measuring voltage at fuse 16 during cranking ??...if that is the case you have a 11.76 “voltage drop” across the ignition switch...or did you measure the voltage drop (no math involved) with red lead on battery POSITIVE and black lead on fuse 16 ??...if this is correct and you are seeing .24 volts that is your voltage drop across the switch...a little high but not like a 11.76 voltage drop !!...also with key ON if you select “voltage” on the DIC what voltage are you seeing...just curious !!
Sorry for the vagueness. I tested it by putting thlead on the positive terminal and touching the negative lead to the fuse. There was an 11.76V drop when cranking. 12V with key on, then 0.24V while cranking. The battery was at 12.36V since I had been cranking quite a bit to test everything.
Last edited by Chris Scapp; May 15, 2019 at 07:43 AM.
Reason: Forgot to add
Well if you tested the way I had mentioned to me you have bad ignition switch...now you need 2 people to do this test...did you have someone crank while you tested...now this is what I’m reading in picture below with red lead connected to battery positive BUT with my engine running..,a .20 voltage drop across the PCM fuse...with key ON I was reading .05 volts !!...Bill C is our “professor emeritus” on ignition switches...hopefully he will chime in with a diagnosis confirmation...and that MAF voltage concerns me !!
