I HAVE POWER THROUGH THE CRANK FUSE, TO THE PCM AT PIN 76 (12VOLTS) when in the crank postion. PIN 23 ISNT SENDING A GROUND TO THE START RELAY. IF I GROUND IT THE ENGINE WILL CRANK. I HAVE CHECKED ALL HOTS AND GROUNDS AT THE PCM AND ENGINE BLOCK. I HAVE TRIED ANOTHER PCM. FUSES AND RELAY HAVE BEEN TESTED. NEED HELP..

say the starter motor is dead and will not crank and starter is silent or clicks or chatters.
the service manual covers this. I have it. 7000 pages.
here is the serial path, the runs the starter
sorry IMMO on jeeps do defeat the starter ,yes spark/fuel.
scan the PCM cranking and it tells you why it fails.
pape 9b-4 in the service manual matches my list.
1: battery main not dead.
all fuses ok.!
2: battery lugs not lose or rusty., Jumper cable jumps fail?
3: key switch not dead.
4: PRNDL switch not bad, (try cranking in Neutral)
5: starter relay bad.
6: starter bad and easy to hot wire test it ask. all shops know how. it is a stnd ASE test.
now a drawing, from 99 SM

the PCM controls the starter motor relay,100%
8w-30-11, SM PAGE., see this.
the PCI bus he TCM tells the PCM transmission is in Park or Neutral SAFE, if not PCM will never close the starter relay or PCI bus is dead, scan the PCm first.
pdc fuse 8 not blown starter power.,solenoid pin.
jb fuse 31 not blown key power.
that is it , a voltmeter can find the point of failure.
key st pin sends crank 12vdc to fuse 31
TRS is transmission PRNDL PCM goes to ground
if tranny in P/N and PCM sees it. else not.


not scanning the PCM is huge fail hear see TCM monitors 3 pins for failures. and more.
even says battery is failing too.

Starter Voltage Drop

Starter relay ? Transmission range switch ? IS battery voltage getting to the starter solenoid S terminal ?

How to voltage drop test starter motor circuit

Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine . Under system click on engine ,then under subsystem click on starting .

Starter
When the ignition switch is moved to the RUN position, battery voltage is applied to one side of the Crank Relay in the underhood accessory wiring junction block through circuit 3, the PCM-BCM Fuse in the fuse block, and circuit 439. When the ignition switch is turned to START, voltage is fed to the powertrain control module connector C2 terminal 23 through circuit 5, the CRANK SIGNAL Fuse in the fuse block, and circuit 806 through the underhood accessory wiring junction block. Power is always provided from the CRANK MaxiFuse in the underhood accessory wiring junction block to the common side of the Crank Relay contacts. When the powertrain control module sees the crank signal and determines that conditions are OK for a crank, it supplies ground through circuit 625 to the Crank Relay. The Crank Relay now has both power and ground to the relay coil, causing the relay to pull in. When this happens, and the gear selector is in either PARK or NEUTRAL, the power at the relay common contact is passed through the normally open contact , circuit 1737, the transaxle range switch and circuit 6 to the S terminal on the starter solenoid.

What relay did you replace ? Starter relay ? Removing the relay you may have changed connector position in the fuse / relay box where the relay plugs into . Wiggle the relay see if that does anything . At the relay base jump pin's 30 & 87 with jumper wire , it should crank the engine over . If you look on the bottom of the relay you will see 4 set's of numbers 30 & 87 are load side of the relay . If you were to test with a voltmeter ,pin 30 would have Battery voltage ,Pin 87 goes to the S terminal on the starter solenoid . Pins 85 & 86 are the control side .When you turn the key to start B+ voltage goes through the run / start diode ,located in the AUX relay box 1 through the digital transmission range sensor to pin 86 of the starter relay ,pin 85 goes to the PCM .Where the PCM supply's a ground energizing the starter relay closing the contacts inside sending B+ voltage to the starter solenoid S terminal . Do you have a automatic trans or manuel ? Move gear selector to neutral , check out wiring diagram here http://www.bbbind.com/free_tsb.html Watch videos on youtube for basic electrical testing , voltage drop testing etc.... How to test a relay . Test the circuit ! How to voltage drop test starter motor circuit

Hi Andre , I'm guessing your Caddy won't start because of your wanting to replace the neutral safety switch .Before replacing or trying to,did check for B+ voltage coming through the switch to the PCM ? There are a lot thing's that could cause your caddy not to start !
Moving the ignition switch to the CRANK position sends a 12 V signal to the PCM ignition crank request input. The PCM verifies that it has received a valid theft password from the vehicle's theft deterrent module and that the transmission is in the PARK or NEUTRAL position. The PCM then grounds the control circuit of the START 1 relay. When the START 1 relay is energized it completes the B+ voltage circuit to the starter solenoid S terminal.
There could be a anti-theft system problem , is the security light lit on the instrument cluster ? Check the start 1 relay in the under hood fuse box . Did you test for Power an control at the relay ? Find the relay an pull it out of the fuse box , look on the bottom of it . You should see four set's of numbers 30,87 an 85,86 , 87 should B+ voltage ,30 goes to the starter solenoid .If you jumped those two the engine should crank over . If the starter is good an battery cables are good etc... I'm talking about jumping where the relay plugs into , not on the relay . Pin 86 should have B+ voltage with the key on , pin 85 goes to the PCM . PCM gives a ground to pin 85 energizing the relay sending B+ voltage to the starter .
Do you know where the PCM is located ?
Transaxle Range Switch Parity Input
connector 1 blue pin 41 ,white wire

Yes you need to test first because what you call neutral safety switch is really called
Transmission Internal Mode Switch
The transmission internal mode switch (IMS) is a sliding contact switch attached to the lower control valve body, within the transmission. The manual valve link assembly then connects the IMS to the manual valve. The four inputs to the PCM from the IMS indicate which position is selected by the transmission selector lever. This information is used for engine controls as well as determining the transmission shift patterns. The input voltage level at the PCM is high (ignition voltage) when the IMS is open and low when the switch is closed to ground. The state of each input is available for display on the scan tool. The four input parameters represented are Mode A , Mode B, Mode C and Mode P (Parity).
If the PCM detects an IMS transitional state between NEUTRAL and D4 while the vehicle is in motion, then DTC P1823 sets. DTC P1823 is a type B DTC.

How is the battery ? Do the headlamps shine bright ? Did you check the crank relay an the crank fuse 40amp ? one of the big one's ,maxi fuse . Under hood fuse / relay box . Check to see if voltage is coming through the transaxle range switch.

When the ignition switch is on, battery voltage is applied to one side of the crank relay in the underhood accessory wiring junction block through circuit 3, the PCM-BCM Fuse in the fuse block, and circuit 439. When the ignition switch is turned to START, voltage is fed to the powertrain control module connector C2 terminal 23 through circuit 5, the CRANK SIGNAL Fuse in the fuse block, and circuit 806 through the underhood accessory wiring junction block. Power is always provided from the CRANK MaxiFuse in the underhood accessory wiring junction block to the common side of the crank relay contacts. When the powertrain control module sees the crank signal and determines that conditions are OK for a crank, it supplies ground through circuit 625 to the crank relay. The crank relay now has both power and ground to the relay coil, causing the relay to pull in. When this happens, and the gear selector is in either PARK or NEUTRAL, the power at the relay common contact is passed through circuit 1737, the transaxle range switch and circuit 6 to the S terminal on the starter solenoid.
Passlock Theft Deterrent System
This vehicle is equipped with the Passlock theft deterrent system. This system contains a Passlock sensor. The Passlock sensor is part of the ignition lock cylinder assembly. The Body Control Module (BCM) interfaces with the Passlock sensor.
When turning the ignition switch to the START position with the proper key, the Passlock sensor generates an analog voltage signal, which is sent to the BCM. This analog voltage signal is of a specific value to the vehicle, and varies from vehicle to vehicle. When attempting to start the engine, the BCM compares a preset stored analog voltage value with the signal coming from the sensor. Because both values match, the BCM sends a fuel enable password via the Class II Serial Data Line to the Powertrain Control Module (PCM). As a result, the PCM enables the crank relay, and allows fuel delivery to the engine.
When attempting to start the engine by means other than using the proper key in the ignition switch, the Passlock sensor sends a analog voltage signal of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values do not match, the BCM sends a fuel disable password via the Class II Serial Data Line to the Powertrain Control Module (PCM). As a result, the PCM disables the crank relay, and does not allow fuel delivery to the engine.
For more information regarding the Passlock theft deterrent system, refer to Theft Deterrent in Body and Accessories
This starting system is computer controlled , if you are not familiar with this I suggest you take a GM dealership or an ASE certified repair shop .

Did you check for power at the crank relay in the under hood fuse block ? Two pins should have batt + One from CRNK fuse 30amp in the under hood fuse block #2 from PRK/NEUT fuse 10amp ,this power supply comes through the park neutral switch . One pin is to the starter an the other to the PCM / ECM ! The PCM/EMC get's a command from the BCM over the serial data communication bus to give a ground to that pin to energize the relay an crank the vehicle ! Do you have any lights lit on the instrument cluster , check engine , security , a yellow wrench ? You can test right from the relay socket ! I will send a link on how to do it . It won't be for the same problem , but you should get the idea ! This could very well be a computer problem . You need to know how the system functions. When you turn your key to crank the engine , it is an input to the BCM - body control module . The BCM then tells the engine computer to ground the pin at the crank relay, an if there is no problem with the anti-theft system the engine computer will ground the pin cranking the engine ! You always have things tested before replacing parts, that is a needless waste an cost more in the long run ! You should have taken it to a ASE certified repair shop ! VEHICLE RELAYS Testing from the relay base VEHICLE RELAYS Operation Diagnosis

Check for a blown fuse.

Have you checked for spark or fuel reassure? Do the brake lights come on?

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Hello! I sent a test procedure to you Wednesday evening but It appears you did not receive it ..This is the path for Battery and Ground to pull the crank relay which applies +12 volts to the starter solenoid..Either there is a fault in this path or the starter itself was damaged in the collision...Leaving the ignition switch when in start ...+12 volts on the Yellow wire goes to the Crank fuse (10A)...Other side of fuse is Purple wire to PCM C-2 Pin # 23...+ 12 volts at this point...PCM sends a ground on C-2 pin #76...Yellow/Black wire to crank relay....+ 12 volts from the PCM ABS fuse (10A)...via Park/Neutral switch to crank relay...Relay pulls and applies +12 volts on the Purple wire that goes to the starter...That +12 volts, if there,indicates a starter damaged in the collision...If not there chase it back until you lose it...Would you be so kind as to not rate my solution until the test procedure is accomplished...Send a comment..saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Check fuse # 28 (15 Amp) with a test light. (Located in the Power Distribution Center (PDC) on the left side of the engine compartment) It should have power only when the ignition switch is turned to the START position. If there is no power there, then you probably have a bad ignition switch. The only other fuse involved would be fuse #8 (40 Amp) which is also in the PDC. If this fuse is blown a whole lot of stuff is not going to work - not just your starter. The starter motor relay (Also in the PDC) is controlled by the PowertrainControl Module. The wiring diagrams show it as a 5 pin relay whereonly 4 of the pins are used. If you check for power and ground at the connector pins for the relay, there should be one pin that is hot all the time. This is the power from fuse #8. a second pin should be hot with the key in the RUN and START positions. This would be the circuit running through fuse# 28. One pin should have continuity to ground (your test light should light up if you hook it to the battery positive terminal and probe this terminal.) This is the circuit that goes down to the starter. The 4th pin will have no continuity to anything at all until the ignition is placed in the START position, when it will have continuity to ground. This is the relay control circuit from the PCM.
If you dont have power at the relay connector as described, then you must repair the circuits between the fuses and the relay. If you don't have the grounds as describedfor the starter circuit, you ether have an open circuit going to the starter or a bad starter. If you are not getting ground on the control circuit from the PCM, it could be several other things causing your no-crank problem. It could be an open circuit between the starter relay and the PCM or it could be that the PCM is not allowing an engine start for one reason or another - The PCM will have to be scanned to find out what the problem is.