I need help with an old starting issue problem
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From: Kingsland, GA
I need help with an old starting issue problem I posted this a while back, but after trying some suggestions, my swap still won't start. It's a 91 Z28 ls1/t56 swap. I'm using the 4th gen dash and every inch of wiring out of the 4th gen. When I first wired everything up, the instrument cluster lit up, reverse lockout kicked in, and the fuel pump primed...but the engine would not crank. I grounded some wire (don't remember which one) from the bcm and that allowed it to crank...but it wouldn't start. Then the fuel pump stopped turning on. I thought that maybe the vats was not fully disabled, so I wired in the proper resistors (security light now stays off) but still no fuel pump. Now, the reverse lockout does not engage (or disengage depending on how you look at it.)
I have checked all the fuses, and swapped relays around and nothing seems to work. I don't know if this is relevant, but my oil pressure gauge maxes out and the fuel gauge bottoms out with the ignition on. I don't think this matters either but: instrument cluster and bcm are out of a '99, engine harness and ecm are out of a '00, and the body harness is out of a '01.
What am I missing? As far as I know, everything is hooked up correctly, grounded properly, etc.
I have checked all the fuses, and swapped relays around and nothing seems to work. I don't know if this is relevant, but my oil pressure gauge maxes out and the fuel gauge bottoms out with the ignition on. I don't think this matters either but: instrument cluster and bcm are out of a '99, engine harness and ecm are out of a '00, and the body harness is out of a '01.
What am I missing? As far as I know, everything is hooked up correctly, grounded properly, etc.
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Okay, I messed with it some this morning...rechecking fuses and connections. Still had the same problems. Then I found my hptuners cable (which I had lost when I moved a few months ago) so I thought I would scan for codes and see if the injectors were firing and stuff. Well I plug in the cable and twist the key, and low and behold the fuel pump primes and the reverse lockout disengages. But the oil pressure gauge still maxes out and the fuel level still plummets below empty.
Adding insult to injury, my battery is too dead (10v) to start the car. But it did have enough juice to let me know the injectors have some pulse width at cranking. One thing that is weird, is my tps reads 50% at closed throttle. Any ideas on that?
This is the only dtc that came up:
[HUD] U1000 - Class 2 Communication Malfunction (History) (Current) (Immature)
Adding insult to injury, my battery is too dead (10v) to start the car. But it did have enough juice to let me know the injectors have some pulse width at cranking. One thing that is weird, is my tps reads 50% at closed throttle. Any ideas on that?
This is the only dtc that came up:
[HUD] U1000 - Class 2 Communication Malfunction (History) (Current) (Immature)
Well, first off fix the low voltage issue. Low voltage can cause alot of weird things to happen. Second check and see what the fuel pressure is. Does the pump continue to run while cranking the motor? That will cause a no start situation like this. Third see if you have spark. That is while cranking too. You would be amazed how many times folks forgot that the unit has to also get power while cranking. As for the oil pressure gauge. The Oil pressure gauge operates like this. The dash gauge uses a resistance based calculation off the vehicle ground vs the ground coming from the oil pressure sensor to determine the oil pressure. If you have a cut wire or if you don't have the instrument cluster 100% properly grounded then it will peg out the gauge. Could also be a screwed up Instrument cluster too. As for the fuel gauge issue, that's alittle more involved because the sender as you probiably know doesn't get hooked to the dash, but to the PCM. The PCM tells the Instrument Cluster what the fuel level is through the Class II serial data bus. The U1000 error might explain part of that issue. It sounds to me like you have some wires that have been cut or damaged. Good luck because tracing down wiring issues I know can be a PITA.
PS, forgot to mention also ensure that the injectors are getting power while cranking also. The PCM is just merely sending the signal to the injectors that doesn't mean they are opening.
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Thank you...that helps a lot! The injectors I will have to check for voltage. So you are saying that just because it shows pulse width, that doesn't necessarily mean they are opening? Do you know by chance where the ground for the instrument cluster is? I do have some small grounds not hooked up, but I don't think they are relevant. A couple are from the group of wires that go down the console, and a few are toward the back by the tail light harness. There are a few grounds on each side of the bottom dash mount. I checked a friend's car and I think I remember him having more grounds there than I do...I need to find out what all those are for. I'll check and see if the pump is still running while cranking too. I sold my service manuals about 6 months ago...I knew I should have kept them. Thanks again.
What do I need to check for that u1000 code?
What do I need to check for that u1000 code?
To check the injectors just pull off one of the injector connectors. You will see a pink or orange wire and another colored wire. The pink or orange wire is the hot wire to the injector. The way the injectors are fired off is the injectors are always hot with 12 VDC+ when the key is in the on position and in the start position. The way the injector is fired is the PCM basically sends a ground signal to the injector firing it off. The PCM has no idea if it is actually firing or not. The coil packs are the same way. If you have the common rail like the 99+ motors just unplug that large white plug on the valve cover. The orange or pink wire (I can't remember which it is anymore) is a 12 VDC+ and the individual coils are fired off by ground signals being sent to the coils. Check to ensure you have current on both while cranking with eithor a test light or a multimeter. Hope this helps alittle.
PS also ensure the PCM is 100% grounded where it should be.
PS also ensure the PCM is 100% grounded where it should be.
Now to address your IPC issues. I'm assuming that because you installed the entire 4th gen dash that you also integrated the BCM right? In any event I'll post the pinout of a 01 IPC and see if this helps you. That U1000 code could be anything though. Does the car have the 4th gen ABS pump? The ABS believe it or not operates on the class II circuit. So does the cruise control module and the airbag module, the BCM and the IPC ect ect ect.
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That helps a bunch! I'll work on checking all that stuff for the next couple of days. Yes, I did keep the bcm. But I do not have abs, or AIR, or air bags, or cruise. So I have some unused connectors. There is something that I am not using that is on the 4th gen cars...it's located on the driver side frame rail (bottom side) kind of below the abs junk. It's a box/module of some sort with a large plug...similar in size to the abs.
Last edited by fast377; Oct 7, 2007 at 08:03 AM.
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From: Kingsland, GA
Okay, I got it started...as much as it didn't want to start, it finally did. Part of the problem I think, was that I didn't have the IAT hooked up. So the ecu thought it was -38 degrees. I put a resistor in to bring the temp up to 70 and that seemed to work. I have a couple of problems though. First it doesn't want to rev. I'm assuming that can be fixed with a tune (motor is basically stock, but I bought a cam off here...supposed to be a thunder cam, ls6 intake, lt's). Second, it won't start unless the scanner is hooked up. If I don't have my scanner hooked up the fuel pump won't come on. So, correct me if I'm wrong, but I have something that isn't grounded somewhere. Trouble is where? Scan showed everything to look decent...I think (I'm still learning the tuning stuff).
Actually, after looking at the scan, something is up. Fuel trims stay at 0 and map kpa is way high (I think)...fluctuates from 39-97 (depending on throttle position.)
Actually, after looking at the scan, something is up. Fuel trims stay at 0 and map kpa is way high (I think)...fluctuates from 39-97 (depending on throttle position.)
Last edited by fast377; Oct 15, 2007 at 01:56 PM.