greddy32 Posted April 25 Author Report Share Posted April 25 What should voltage be on 45 whioe cranking? And am I testing it correctly? Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 25 Report Share Posted April 25 Pin 45 is from the ignition switch, it should show close to battery voltage whenever the ignition switch is on. If it drops below about 7.5V the ECCS relay will drop out. Note on a BNR32 this wire also supplies the fuel pump, oxy probes, idle valve, AC relay, boost valve & EGT sensor, so it is a fairly overloaded circuit, not uncommon to see low voltage on it as the ignition switch wears and all the connections along the way get more resistance with age. 21 hours ago, greddy32 said: It doesn't show any voltage on 45 while cranking or ever for that matter. 1 lead on 49 the other on 45 while testing Should be measuring between ground and 45. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted April 25 Author Report Share Posted April 25 So I'll retest test with 45 and ground and let you know what it says.. if it's low whats the solution? A new ignition barrel? Also would running all ecu grounds directly to a batt(-) stud help at all? Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 26 Report Share Posted April 26 Confirm if that is the issue first. Will need to do a bit more digging to suggest the best solution. For example if the fuel pump is still supplied by the ignition switch it would probably be best to change the fuel pump supply which will take a lot of load off that circuit - But that may already done for all I know. So at this stage Im still trying to confirm if your issue is on the triggering side of the ECCS relay or on the high power side or something like a ground issue. 1 hour ago, greddy32 said: Also would running all ecu grounds directly to a batt(-) stud help at all? I dont remember what the grounding scheme is like on the GTR but generally older Nissans main ground point is on the engine as some devices including the CAS and ignitor ground through their body/mounting. Changing to batt -ve wouldnt be recommended if this is the case. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted April 26 Author Report Share Posted April 26 Okay my son is asleep for the night so I won't be able to test any cranking until tomorrow. To your example, my fuel pump is getting 12v triggered from the trunk, it's reloomed but I'm assuming it's the circuit you're referring to. Where would I grab 12v from thats not on the same ignition switch? Quote Link to comment Share on other sites More sharing options...
greddy32 Posted April 26 Author Report Share Posted April 26 Off topic but which was is the correct way to wire a radiator fan? 30 batt 87 fan 85 ecu 86 switched 12v Or 30 batt 87 fan 85 switched 12v 86 ecu Quote Link to comment Share on other sites More sharing options...
greddy32 Posted April 26 Author Report Share Posted April 26 45 drops from 12.5 to 7.73 while cranking Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 26 Report Share Posted April 26 That sounds a bit borderline considering a multimeter has quite a low update rate. Just reading back at some of your earlier posts in this thread, you mentioned you had done a test by grounding pin 16 with a bit of welding wire or similar - did the ecu stay connected when cranking when you done that? Quote Link to comment Share on other sites More sharing options...
greddy32 Posted April 27 Author Report Share Posted April 27 It did stay connected but only 1 time for some reason. I've tried a couple times since and the ecu always disconnects Quote Link to comment Share on other sites More sharing options...
Adamw Posted April 27 Report Share Posted April 27 Hmm, thats odd. Can you try setting up ecu logging like below, with just engine speed and batt voltage logged at 100Hz, no control conditions so it just logs all the time the ecu is on. Then do a couple of cranks and download the log. That will at least confirm it is shutting off rather than just a USB issue and if it is shutting off it may capture what was happening to battery voltage just before that point. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 23 Author Report Share Posted June 23 On 4/25/2024 at 5:31 PM, Adamw said: Confirm if that is the issue first. Will need to do a bit more digging to suggest the best solution. For example if the fuel pump is still supplied by the ignition switch it would probably be best to change the fuel pump supply which will take a lot of load off that circuit - But that may already done for all I know. so i have a power post in my trunk thats powered by the oem fuel pump switched 12v. from that post i have my relays for afr, fuel pump x2 and e-fan recieving switch 12v... im assuming this is the "fairly overloaded circuit" (45) you referred to earlier? ill set my logging up as you suggested and send over what i get. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 23 Author Report Share Posted June 23 here are 2 logs set up the way you asked... i think. https://drive.google.com/file/d/12Fp2YXtIt6j6wmp_IuLqKVZOM9PeZrTJ/view?usp=sharing https://drive.google.com/file/d/1ZPXQUzz2A9MUGYiN-LinCrjMwqWi-cQ_/view?usp=sharing Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 24 Report Share Posted June 24 Yes you have a voltage issue there. The ecu shuts off and reboots everytime in both of those logs, in one case where is did get enough voltage to power back up while still cranking the voltage showed 7.2V at that point, so it drops to something lower than that. 19 hours ago, greddy32 said: so i have a power post in my trunk thats powered by the oem fuel pump switched 12v. That will be the main issue, that is a lot of load going through the ignition switch. It would be best to connect all this extra stuff to a relay that gets its supply from the battery and just use the OEM fuel pump switch signal to turn the relay on. Quote Link to comment Share on other sites More sharing options...
Tom's r32 gtr Posted June 24 Report Share Posted June 24 Okay currently my relays are In The trunk near the battery, I'll move afr and fan relays to under the dash and take switch 12v from the cig lighter power (unless you suggest otherwise). I'll used oem 12v switch for fuel pumps only. I'll send a log tomorrow Stupid question....How would I wire a relay directly to the batt like you mentioned? Where would the pins on the relay go? I want to make sure I'm not grabbing 12v switch from another overloaded circuit or a inadequate circuit Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 27 Author Report Share Posted June 27 hey adam so i moved the fan and afr relays to the cig lighter 12v switched source up near the firewall and still no start and the ecu still cuts out also now my fan turns on with the key in the acc position.. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 27 Author Report Share Posted June 27 he adam heres another log of it cranking after i moved the relays relays moved.llg Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 28 Report Share Posted June 28 That is a PC log, not an ecu log as I suggested. A PC Log is no use when the PC is not connected. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 28 Author Report Share Posted June 28 hows that? idk what i messed up on the last one crank today.llg Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 28 Author Report Share Posted June 28 ECU Log 2024-06-27 6;33;00 pm.llg Quote Link to comment Share on other sites More sharing options...
Adamw Posted June 28 Report Share Posted June 28 Your battery voltage is still dropping very low in that log but at least the ecu is staying powered up the whole time now. But it appears that the low voltage is also causing the CAS to drop out. I have marked some areas in pink in the log snip below where RPM shows zero but you can see it is cranking because the voltage is low so RPM should be showing something. 0RPM means there is no signal from the CAS in these areas. I have seen the Nissan CAS drop out at low voltage before so suspect this is probably the case here. There may well be other issues preventing it from starting, but this voltage issue is the first thing that needs investigating. The CAS and ECU power supply comes from the ECCS relay so the issue is likely in that circuit somewhere. You will really want to get someone experienced involved to diagnose this voltage drop as it could be a huge range of possibilities. Quote Link to comment Share on other sites More sharing options...
greddy32 Posted June 28 Author Report Share Posted June 28 okay adam. thank you for your time. side note, Link needs to implement a form of tipping $$ on the forum. you and your team have some of the most rock solid patience with "inexperienced" customers that ive ever seen. thank you and Vaughn for the help. ill report back. Vaughan 1 Quote Link to comment Share on other sites More sharing options...
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