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

LOL! I have to say I'm confused about what's going on with it but the reason you don't understand is probably because the situation is really hard to type about - to understand I think you need to be shown :)

 

Cheers,

James

Did you ever get a result????:)

Dodgy wiring loom :) simple as that in the end lol.

I am often surprised just how helpfull this forum really is, I for one could not do without it.

:)Honestly did'nt think it was the PTU as it is a series 2 Turned out it is.Put in the car myself about 4yrs ago.Now back to a series 1 thanks to Paul@SWZ

So for £30 car back on the road.It did give me a chance to check all the Engine bay wiring and contacts and give the all a fix.:D:D

 

Cheers Paul and thank you for lending me the ECU & CAS they will be back in the post tomorrow.you do run a brilliant service:bow:

 

chaZ:cool:

Glad to hear you're back on the road chaZ. I got mine running again by simply buying a replacement PTU but my car had an issue where it kept blowing PTUs. I have assumed this to be down to high resistance wiring in the loom because after stripping the loom back and reducing the length of wire to and from the PTU it has not blown another PTU (yet...fingers crossed). I must get round to actually replacing the wiring loom.... :D

 

Cheers,

Vern

Glad to hear you're back on the road chaZ. I got mine running again by simply buying a replacement PTU but my car had an issue where it kept blowing PTUs. I have assumed this to be down to high resistance wiring in the loom because after stripping the loom back and reducing the length of wire to and from the PTU it has not blown another PTU (yet...fingers crossed). I must get round to actually replacing the wiring loom.... :D

 

Cheers,

Vern

 

Fortunately I dont have a loom problem.......................yet:D

 

chaZ

I am often surprised just how helpfull this forum really is, I for one could not do without it.

 

Mark it's probably a good scheme to keep your series 1 just in case....:)

 

When I replace with a series 2 I will keep the other as a spare,should have done that the first time around:headvswal

 

chaZ:)