Just to let everyone know, I am now the proud owner of a 1990 300zx TT SWB T-Top Black Jap Import (I'll get some photos uploaded when it's clean)...BUT I've got a bit of a problem with the car blowing PTUs at the moment and I could do with a little help working out what the problem is. I've checked the PTU for continuity and it's dead so I know I definately need a working PTU but would like to find and fix the problem to prevent it from blowing another one. Does anyone have a cheap working S1 PTU I can buy to test the car with? (I know it'll need a S2 eventually but don't want to fork out the extra money in case it blows it again)

 

The PTU is getting it's 12 volt feed on all 6 pins on the input connector and the earth has little resistance between the earth pin and the battery -ve post but from the connector that connects to the output side of the PTU there is a 4.4 volt feed on all 6 pins :confused:

 

It looks like I'm going to have to strip the loom back and find the short/breaking down component that is backfeeding through the loom but I found it a unusual that if the 4.4 volt feed is a problem it would be on all 6 pins so I thought I'd better check on here first.

 

By the way - I know that the usual problem with S1 PTUs is that a dry/disconnected joint inside the unit but I have opened one of the car's previous PTUs and checked the joints and they're all OK but there's still no continuity through that unit either so it looks like the actual transistor bit is fried. My first thought was to check the alternator is charging correctly i.e. not over 14 volts but now it has blown the current PTU I obviously can't check this.

 

Regards,

James

Anyone able to check if the ouput connector of their PTU has 4.4~4.7 volts to it? Could do with knowing this before I buy another PTU and by the way - anyone got a series 1 working unit that they're selling? Or does anyone know the best place to get one?

 

Thanks,

James

Anyone able to check if the ouput connector of their PTU has 4.4~4.7 volts to it? Could do with knowing this before I buy another PTU and by the way - anyone got a series 1 working unit that they're selling? Or does anyone know the best place to get one?

 

Thanks,

James

 

I'm afraid I can't help you with the voltage query but you won't be able to find a new Series 1 PTU. We stock S2 PTU's (£145) so if you need one please let me know.

 

Good luck,

 

Dan

Thanks for the reply Dan, not interested in buying a S2 PTU at the moment as I'm not sure if it's going to blow another one or not. I'm just after a cheap used series 1 so that I can start the car and test what voltage the alternator is giving out so that I can check it's what it should be so I know that it's not excessive voltage blowing the PTUs.

 

Cheers,

James

Just to let everyone know, I am now the proud owner of a 1990 300zx TT SWB T-Top Black Jap Import (I'll get some photos uploaded when it's clean)...BUT I've got a bit of a problem with the car blowing PTUs at the moment and I could do with a little help working out what the problem is. I've checked the PTU for continuity and it's dead so I know I definately need a working PTU but would like to find and fix the problem to prevent it from blowing another one. Does anyone have a cheap working S1 PTU I can buy to test the car with? (I know it'll need a S2 eventually but don't want to fork out the extra money in case it blows it again)

 

The PTU is getting it's 12 volt feed on all 6 pins on the input connector and the earth has little resistance between the earth pin and the battery -ve post but from the connector that connects to the output side of the PTU there is a 4.4 volt feed on all 6 pins :confused:

 

It looks like I'm going to have to strip the loom back and find the short/breaking down component that is backfeeding through the loom but I found it a unusual that if the 4.4 volt feed is a problem it would be on all 6 pins so I thought I'd better check on here first.

 

By the way - I know that the usual problem with S1 PTUs is that a dry/disconnected joint inside the unit but I have opened one of the car's previous PTUs and checked the joints and they're all OK but there's still no continuity through that unit either so it looks like the actual transistor bit is fried. My first thought was to check the alternator is charging correctly i.e. not over 14 volts but now it has blown the current PTU I obviously can't check this.

 

Regards,

James

 

I've got three known working ptu's and none of them have any continuity though most of the pins other than two! I know they are fine as I only tested them Saturday on the car:)

Most of the time its corroded connectors, ptu pins or a fault in the ptu itself thats the main problem!

Hi (Z)Master, you won't get continuity through all of the pins. I'm talking about the actual Nissan (I think) test procedure for PTUs:

As you can see from this it depends on the polarity of the tester probes and the combination of the pins you test. I think that the pin labelled 3/d in the 'in' connector is supposed to be the earth and on the series one connectors it's not so you need to keep that in mind when testing a PTU - however, that's only an assumption. The connectors and pins have been cleaned up throughly and still has not solved the problem :) Any chance someone could test the voltage of the pins of their 'out' PTU connector while the ignition is turned on and see if they get 4.78 volts too'? Would really appreciate it as I want to check this before I put another PTU on it :)

 

Cheers,

James

Hi (Z)Master, you won't get continuity through all of the pins. I'm talking about the actual Nissan (I think) test procedure for PTUs:

As you can see from this it depends on the polarity of the tester probes and the combination of the pins you test. I think that the pin labelled 3/d in the 'in' connector is supposed to be the earth and on the series one connectors it's not so you need to keep that in mind when testing a PTU - however, that's only an assumption. The connectors and pins have been cleaned up throughly and still has not solved the problem :) Any chance someone could test the voltage of the pins of their 'out' PTU connector while the ignition is turned on and see if they get 4.78 volts too'? Would really appreciate it as I want to check this before I put another PTU on it :)

If I get time later I will have a look :)

 

Cheers,

James

If I get time later I will have a look :)

Cheers mate :) appreciate it. As you know it's an expensive part to keep buying new ones of just to have them blow again 5 mins after starting the car!!!

 

Regards,

James

Cheers mate :) appreciate it. As you know it's an expensive part to keep buying new ones of just to have them blow again 5 mins after starting the car!!!

 

Regards,

James

 

Never had an issue with my Zed once i changed to a series 2 ptu.

It's already blown two series 2 PTUs :) Nobody able to check this 4.78V backfeed thing for me? :( could really do with a bit of help here just so I can find the problem!

 

James

It's already blown two series 2 PTUs :) Nobody able to check this 4.78V backfeed thing for me? :( could really do with a bit of help here just so I can find the problem!

 

James

I would have had a look for you but my missus has the zed today and will not be back from work for a while.:)

I know you would mate but out of however many members there are on the forum I can't believe you're the only one that is prepared to test this for me :)

 

Regards,

James

if you were subscribed people might be willing to go more out of their way for you...

LOL @ folk demanding replies etc at the moment. I don't care whether someone is subbed or not BUT it really pisses me off when people whinge about not getting replies within 10 minutes of posting a problem or complaining when people don't respond.

 

Let me state one thing, we have lives to live and jobs to go to, we are NOT here to bend over to every single help post etc. I do my best and thats all I can do!!!!! IF I have a car in pieces and can check the PTU then I will do but I'm damned if I'm going outside and stripping a car to take a few measurements... Especially if its another customers car! Would you be happy if I ripped your car apart while I was working on it so that I could answer a post on here? No I didn't think so either....

 

Give it chance, someone will no doubt answer in time...

 

No offence intended, these posts demanding help are just getting a bit tedious thats all

 

Cheers,

 

Andy

here here andy. You almost do too much - you'd be better saying "it needs a diagnostic - bring it up" ;)

 

Unless its my help query of course :D

Just to let everyone know, I am now the proud owner of a 1990 300zx TT SWB T-Top Black Jap Import (I'll get some photos uploaded when it's clean)...BUT I've got a bit of a problem with the car blowing PTUs at the moment and I could do with a little help working out what the problem is. I've checked the PTU for continuity and it's dead so I know I definately need a working PTU but would like to find and fix the problem to prevent it from blowing another one. Does anyone have a cheap working S1 PTU I can buy to test the car with? (I know it'll need a S2 eventually but don't want to fork out the extra money in case it blows it again)

 

The PTU is getting it's 12 volt feed on all 6 pins on the input connector and the earth has little resistance between the earth pin and the battery -ve post but from the connector that connects to the output side of the PTU there is a 4.4 volt feed on all 6 pins :confused:

 

It looks like I'm going to have to strip the loom back and find the short/breaking down component that is backfeeding through the loom but I found it a unusual that if the 4.4 volt feed is a problem it would be on all 6 pins so I thought I'd better check on here first.

 

By the way - I know that the usual problem with S1 PTUs is that a dry/disconnected joint inside the unit but I have opened one of the car's previous PTUs and checked the joints and they're all OK but there's still no continuity through that unit either so it looks like the actual transistor bit is fried. My first thought was to check the alternator is charging correctly i.e. not over 14 volts but now it has blown the current PTU I obviously can't check this.

 

Regards,

James

 

Ive got a S1 mate, works fine, email me for more details at :-

 

pete2407@email.com

 

Regards

Quavey - what's being subscribed got to do with getting responses? :confused: I wouldn't expect the benefits like being able to sell things on the forum etc without paying subscription but if the help and advice forum is free to use then surely the fact that I'm not subscribed should have no effect on people responding.

 

andyduff - Don't know who has been whinging about not getting replies within 10 minutes but it certainly isn't me. Let me state one thing - I also have a life to live and a job to go to and I know that nobody is here to bend over to every single help post etc. I'm sure you do do your best and I understand that that's all you can do - nobody is disputing that. It's not exactly a difficult or time consuming thing to do though is it and it doesn't involve 'stripping a car'. Also, to be honest I wouldn't be any the wiser if, whilst you were working on my car, you had tested the voltage at the PTU output connector would I? If there was a question in a post that I could easily find the answer to I would do so gladly. No offence taken - but I don't think posts from me 'demanding help' can be getting tedious because I've only posted two threads! :)

 

Regards,

James

James take the leads off the coil caps but leave the leads on th einput sideof the PTU and test again for your 4.4 volts , do a search for ignition wiring their are a few scematics on here and systematicaly take off the connections one at a time , the earthing on a zed is very peculiar and is not at as sraight forward as a mondeo or escort os some such , many strange faults have been cured by the addition of a grounding kit ...im 4000 miles away from my zed or i would have looked to see if i had the 4.4v feedback you are getting

 

Steve

Cheers for the reply Steve. My next step was to do exactly what you said and track where the backfeed is coming from but the thing was that I wasn't sure whether the feed was supposed to be there or not - that's why I posted on here because I thought I'd better check that the 4.4~4.8 volt feed was actually a fault rather than wasting my time testing all sort of connectors etc in the engine bay and then finding out that the feed is actually supposed to be there :) I think the previous owner has already added a grounding kit in an attempt to cure this problem but I will check and post back on here. I'm assuming from your reply that there is not supposed to be any feed to the output side of the PTU?

 

Cheers,

James

Update - Had a chance to look at the zed again this morning and found that the 4.78 volts feed I had at the output connector of the PTU had disappeared! I shook the loom and the multimeter reading was all over the place so I started to remove some of the outer sheathing of the loom and found that across the top of the engine near the bulkhead the loom is bodged together i.e. wires are taped together :mad: Looks like new eninge bay wiring loom time! :cry:

 

Cheers,

James

Update - Had a chance to look at the zed again this morning and found that the 4.78 volts feed I had at the output connector of the PTU had disappeared! I shook the loom and the multimeter reading was all over the place so I started to remove some of the outer sheathing of the loom and found that across the top of the engine near the bulkhead the loom is bodged together i.e. wires are taped together :mad: Looks like new eninge bay wiring loom time! :cry:

 

Cheers,

James

Have you checked every coilpack connector as well?

Checked every coilpack connector for what sorry? The backfeed? I hadn't done before but I did this morning and there was no sign of a backfeed at the PTU output connector or the coilpack connector but another thing I noticed is that all the pins on the PTU output connector had continuity with the chassis/ground/battery -ve and none of the PTU output connector pins had continuity with any coilpack connector pins except the earth - I know I haven't explained it very well but I can't think of how else to put it so good luck understanding what I mean lol :) Like I said it looks like it needs a new 'engine room wiring harness' but I'm still on the lookout for a cheap series 1 PTU to run it temporarily after I've tidied up the mess of a loom that's on it at the moment :)

 

Cheers,

James

all of this has confused me, i feel very stupid now

all of this has confused me, i feel very stupid now

 

 

I'm with you :rofl:

I'm with you :rofl:

Do I smell sugar puffs???:tongue:

:tongue: :rofl: :rofl: :rofl: