I've been working on this car and reading up on this forum for a few years. It's not really a C5 but the guts are. Everything underneath the skin is C5. Drive train and electronics are all 2002 C5:

Engine Harness and fuse panel
Dash Harness and fuse panel
PCM
TAC Module
BCM
DIC
Fuel Tanks
Ignition switch
Steering column

Nothing on the harness is cut every connector is connected like it was on the C5. I did have to extend the rear harness 10" due to wheelbase differences.

I'm finally at the point of starting it and my symptoms are it cranks fine but does not start. If I spray some starting fluid into the TB it starts and runs but dies once the spray runs out. I do have HP Tuners and have Vats disabled. I'm getting the reduced power, and associated messages displayed on the dash. When I try to go into diagnostics, "Diagnostics" pops up for a second but never goes into it. It also reads Batter Voltage 1.3 on the screen. The battery is fully charged and new and reads 12.4+ at both the battery and the fuse panel.

I also converted most of the body black ground packs to a ring terminal connector and bolted directly to the frame, still need to do the ones by the headlights.

I don't have the factory alarm, door or seat modules.

Any thoughts were I should concentrate my troubleshooting?







1941 Coupe

 

Cool car! Looks like a fun project.

If the engine runs with starter fluid, well, you're not getting gas to the cylinders.

Does the fuel pump turn on with key on? Does the fuel rail pressurize?

Are all the modules/harness/ignition switch/keys/etc... out of the same exact vehicle? If not have they been programed/VIN matched?

If you find the issue to be with the security system or PCM, I believe there are replacement PCMs for vehicles like yours that will perform basic functions and may be an easy option.

 

MAN!! That paint is a mile deep!!!!!!

What modules did you retain and what ones did you delete> The BCM/PCM needs a security hand shake.

BCM PCM SYNC PROCEDURE
The BCM and PCM are NOT plug and play modules and must be programmed using the tech II/ There is an Emergency Sync procedure that you can use if you have to install a BCM on the road without a TECH II:
-----------------------------------------------------------
BCM/PCM RELEARN PROCEDURE


You will need to conduct the PCM/BCM relearn process. This matches their handshake ID's and allows them to talk to each other.

Do this before you worry about VATS issues:

1. Turn on the key for 11 minutes.
2 Turn off the key for 30 seconds.
3. Repeat 1&2 two more times.
4. Turn on the key for 30 seconds.

The car should start and run with the new BCM. Good luck and report back on your progress.

This will sync the PCM to the New BCM

If you changed just the BCM all of your RPO options will not be retained. You will need a TECH II to program them into the new BCM.





Do you still retain the VATS circuit? Resistor chip in the key needs to sync up with resistance value programmed into in the BCM. If you have a Instrument Panel, is the security light on the IPC on or flashing????????

Column Lock functional?? The BCM is looking for the column lock signal. If it shuts down when you move the car greater than 2mph, that may be an issue also.

When you turn the KEY to ON, you SHOULD hear the fuel pump PRIME for 2-3 sec and then stop. If its primed, you should have 60ish psi at the fuel rail scrader valve on the front of the drivers side fuel rail.

Can you still use the DIC in the IPC to read and display the DTCs? If not, read the PCM DTCs and BCM DTCs and post them. Try to clear ALL of them and post exactly what come back. Current and or History.

 

I believe that you can use the PCM as a stand alone module but you will need to use tuning software to TUNE out VATs and BCM security features.

Im sure that EFI Live or HP Tuners experts will provide more info on that procedure.

 

Vats has been disabled via HP Tuners. The BCM is not original to the car, but should be the right part number for that year.

I did perform the relearn process, all 30 minutes of it. I'm not getting fuel to the rail, the fuel pump does sound like it primes. I can jump Relay 35 at the under hood fuse box and I can hear the pump. Column is not locked I can go side to side.

I also have the same year IPC and it flashed Security when I first turn ign to on, gauges do a full sweep then I get the Reduced power Message, Check Tire pressure, Low Voltage, Service Engine Soon. I can clear each message but it won't go into diagnostics, it displays "Diagnostics" for a half second and goes away and back to Low Voltage. I thought I was on to something while trying to waken the BCM in case of sleep, I pulled Fuse 25 under dash and also found a blown 9 BCM fuse, replaced it no changes though.

 

I would NEVER use starting fluid!!!!!!!!

 

What IGNITION SWITCH are you using? If its a C5 Switch, it could have burnt/pitted contacts which you can clean.

Measure the IGNITION SWITCH supplied fuses with a DC Volt meter to ground. You should have full battery voltages on each fuse:

Heres the ignition switch schematic:

 

On top of each fuse are two slots (test points). Measure each slot to chassis ground The hot at all times ones and the ignition switch ones

 

Progress!!
I found another blown fuse 19 IPC, which explains why I couldn't go into diagnostics. I'm now able to go into diagnostics, the only codes were:

PCM P 1220 HC TPS(The throttle position (TP) sensor)
PCM P 1221 HC TPS (The throttle position (TP) sensor)
Sensors are new, so I'll check those fuses and wiring I don't think this would cause a no start though. I have two tac modules I can try.

BCM B 0502 HC (Cleared and not needed in my case no door modules)

A few no comms, from the things I'm not using and expected
Radio
Hvac which I will be using, panel just wasn't plugged in yet
LD
RD
SCM
RFA

Going to get new batt this one is only reading 12.2 on full day of charging...

 

WELL,,,, heres the cause of the reduced engine power:

PCM P 1220 HC TPS(The throttle position (TP) sensor)
PCM P 1221 HC TPS (The throttle position (TP) sensor)

The accelerator peddle, throttle motor, Throttle position sensor and TAC module all have to be working to normally run the engine.

Bill

 

I'm almost there, I swapped out the battery, no more reduced engine power, no DTC's

I'm using the oem two tanks and pump with all the original lines. I'm not sure about this fuel pump it seems to pulsate when I first turn the key instead of steady whine to prime it up. Pump is not new, even when I command the pump from HP tuners it sounds like pulsates. Still no Fuel pressure at the rail. I only have about 1/8 tank of gas in case i need to pull pump out to replace. Maybe I need more gas?

 

YES MORE FUEL! Also check the fuel pump GROUND G-401. Its a STUD & Eyelet ground on the drivers side of the frame just to the rear of the rear tire.

 

Can't help with the problems but wanted to say it is a cool looking car

 

Back at it again..

I'm making progress but for intermittent starting issues, the car is now fully assembled only driven in the driveway. I've since cleaned the ignition switch contacts, replaced the battery, new fuel pump and installed the LCM5. The other day it started fine, I drove it out of the garage, and parked it back inside after a few start up and shut downs.

Today I go to start it and it cranks fine, has fuel at the rail, has spark but won't start, no DTS's. However in the DIC battery voltage reads 11.9 all my fuses for starting all read 12.10 on DVM. I'm leaning toward less than 12+volts at the pcm? I also see a message - Fuel System status 'OL - Not Ready' and Control Module Voltage - '11.8v' in HpTuners?

 

Sounds to me like you are having some sort of a SECURITY ISSUE.
VATS.

Now,,, Each module has 2 or more POWER 12 VDC fuses and a GROUND.

Look in that years service manual electrical power section and find out what ALL fuses that you have for each used module. MAKE SURE by using the volt meter and read EACH FUSE to ground at the test points that all the fuses are getting POWER.

Measure BOTH test points on the fuse to ground to insure that the voltage is coming into and going out of the fuse. Make SURE that the voltage is equal to battery voltage.

Some fuses are HOT all the time and some only when the ignition is on.

If the security light is ON when the ignition switch is ON, THATS A BIG PROBLEM! What does it do??

Bill

 

Vats is disabled via HP Tuners, all the fuses that are related to starting when the ignition is in the on position read battery voltage on both sides of each fuse I/P fuse block 9,13,19,21,22,23,25 Underhood 17,18,19,22,13,16. All maxi's have 12v on each side too.

Security Light is not on. Cranks fine, 50+psi at the rail, wont' fire. How about the DIC reading 11.9 vs batt? voltage of 12+?

 

How about the DIC reading 11.9 vs batt? voltage of 12+?

That voltage is a direct result of the IGNITION SWITCH voltage drop due to less than desirable contact connection. Read the critical voltage readings AT the coils!

Are you sure that you have a good ground connection at the BACk of the drivers cylinder head?????? G 107

Get the meter out and start exploring:









Bill