Never rains but it pours... I went for a 40 minute drive after disconnecting my trickle charger (which was showing a fully charged battery) . Battery is a Deka 9A48 Intimidator AGM and is 2 & 1/2 years old. After 10~15 minutes, the red battery/alternator warning light illuminated (steady). After another 5 minutes I pulled over and fitted my cigarette lighter voltmeter. The voltmeter doesnt fit very well, so I had to push on it to make it work (so I couldn't get a constant reading as I was driving). I started heading home. The voltage was around 13.7, but occasionally dropped lower, even putting on the voltmeter red LED (I wasn't sure if it was the poor connection of the cigarette lighter). Revving the engine didn't seem to generate a higher voltage than 13.7. There were no other fault lights. I don't know how accurate this voltmeter is. At home, 20 minutes later, I checked the battery at my rear battery bus bar (in the engine bay) and it was 12.9v with the ignition off and 12.3 volts with ignition on (HVAC off) I haven't lifted the car yet to look at the alternator plugs or inspected the battery terminals, but I've checked the voltages at the next plug upstream of the alternator. Wiring diagram here: https://www.dropbox.com/t/6sR5X9Wn2NzsxWDF Connector 41029 R (red) wire, ignition off = 12.9v i.e. small wire from battery GV (green/yellow) wire, ignition on = 12.3v i.e. ignition power from key G (yellow) wire, ignition on = 12.3v i.e. wire going to battery/alternator warning lamp Voltage is clearly coming out of the alternator as it increases the battery voltage to 13.7, but something is putting on the light. Any suggestions as a next step before I lift the car in the air? I'll see what voltage the battery goes to with the trickle charger plugged in. Thanks!
I had the exact symptoms and problems as you on my 92 model. Turns out it was the alternator something internally with the voltage regulator was faulty. Rather than rebuilding I opted to replace with a brand new after market alternator. I got lucky as I had the AC Delco style alternator. Mine, like yours was charging and never left me stranded but it was very worrying seeing that light on all the time!
I had those symptoms and it turned out to be the “sensor” wire (G, going to the bulb) that had failed inside the insulation. Basically, the heat & vibration snapped all the strands in the wire right at the back of the alternator a cm or two out of the green connector. The wire looked fine outside, insulation intact etc. but inside it was broken. The failure started intermittently with the battery light coming on occasions until it lost connection completely.
Bob, this happened to me too at Watkins Glen about three years ago. Here are my technicians fixing the problem... Image Unavailable, Please Login They used a wire continuity tester and empirically determined that the broken wire was in the alternator area for the same reasons you mentioned. They slit open the insulation, spliced the broken wire, and taped up the insulation. They installed a new harness when my car got back to the shop. Barry
Hi Ian, I think you probably used the INNOVA 3721 Battery and Charging System Monitor I recommended a few years ago... Image Unavailable, Please Login To get mine to operate properly, I had to clean out the lighter receptacle. The cigarette lighter disappeared several years ago and the receptacle gathered a lot stuff at its base. Barry
Thanks, Matt. I may go for a straight alternator replacement, simply because of cosmetic reasons. Last time I checked, my alternator looked like the oldest item on the car It was letting the team down. Thanks, Bob. That was definitely on my to-do list. The only difference was that this was not intermittent. The battery light came on and stayed on (although the brightness seemed to change slightly). A harness change sounds a little drastic, Barry. The harness has 6 items attached to it, not all easy to get to: Speed sensor, oil pressure transmitter, water temperature transmitter, aircon compressor, starter and alternator. Probably around $1000 Australian now for the harness (to be ordered from the factory). Yep, that's the one. My cigarette ligher works perfectly after I adjusted it, so I'm reluctant to do further adjustments. I'm in an automobile association, I suppose I could get them to check out the battery for free. It's only 2 & 1/2 years old, but it may have been sitting on the shelf for a while. It was on special. It's never been off the trickle charger, so, in theory, it should be ok. It also came back up to 13.2 volts overnight on charge. Thanks to all. Cheers
I used the wrong term, Ian. It was just the alternator cable with its connector that was replaced. This has happened twice in the ten years I've owned the car. The alternator light was coming on intermittently as the broken wire was periodically making contact at the fracture line. It'll probably happen again despite the shielding in place. My car spends a lot of time running at high RPMs generating lots of vibration and heat at the affected area. Barry
Do you mean the thick one which supplies power to the car? Well, I've found at least one problem. I was inspecting the plug on the alternator and one of the wires came out of the back of the plug. Image Unavailable, Please Login The contact (socket) had snapped in half ! The insulation on the wires looked a little dodgy, too. It's going to be difficult to trim back the insulation far enough to put new contacts on. There is something like potting compound inside the harness. I may have to splice some wire in. Thankfully, you can get Nippon Denso plugs on eBay with prewired plugs to make things easier. I pulled the old contacts (sockets) out of the old plug. It took me a while to figure out how to remove them. I had dozens of pin release keys but, eventually, I found a two prong key which released a locking clip. You can see the locking clip in white plastic in this photo: Image Unavailable, Please Login The pic above shows 4 contacts, but there are only 3 holes. The 4th must be a spare. I released the clip using the tool at the back of the plug (middle hole).... Image Unavailable, Please Login Then you can release the 3 contacts individually (I used a jewellers screw driver to push the plastic locking clips out of the way). You do need to access the alternator from underneath the car, but the connector is accessible without taking off any underbody panels. Oddly, the wire colours don't match up with the wiring diagrams. Image Unavailable, Please Login Looking at the front of the plug, with the clip on top, the wire colours are red, red/black and black. I'll have to do some wiring checks tomorrow to figure out what they are. Now waiting for a new connector.... Hope this was the only problem. Don't forget to disconnect the battery!
^ Yes, Ian. That's the cable and it looks like you found the problem. In my case, the wires going into the plug were intact. The broken wire was about four inches away from the plug. The technician slit open the cable covering and felt where one of the wires could be bent sharply. That's where the break was. He was able to do some splicing, taped everything up, and got me back onto the track.
That's the problem I was describing & experienced. If you take a sharp knife and cut open the insulation of that wire going back 5 or 6 cm from the connector I will bet you a 6-pack of VB that the strands in there look like crap (if they are even making the circuit)... The other two wires will also be in pretty bad shape.
Ian, Don't bother replacing the connector. Get a new cable. As Bob said, the strands in all of the wires will be in bad shape. Barry
I'd have to pull the engine to bits to get the new harness fitted, Barry.... unless there is a connector not shown in the wiring diagrams which divides the harness into sections. The water temperature transmitter and the aircon compressor sections will be hard to get to. The water temp transmitter is at the front of the engine in the V. Image Unavailable, Please Login Maybe on the next major
This is what the harness looks like on the 348. It runs from the famous 9-pin connector at the suspension tower and then all over the engine. Th alternator connector is the large green plug. It came with the Denso 140 Amp alternator kit I bought. Image Unavailable, Please Login
All the online photos of 2nd hand 355 equivalent harnesses show the round, green alternator plug. I wonder if a harness with my type plug is even available from the factory. F355 P/N 152187
For reference: On the non-circular plug: Red is the wire from the warning light (formerly yellow/green) Red/black is the wire from the ignition (formerly yellow) Black is the wire from the battery (formerly red). Image Unavailable, Please Login
All the 355 I have seen have the green round plugs. The non-round plug looks like a non-original plug to go with the non-original alternator. There is a Toyota/lexus model that uses the same alternator with a different plug. That may explain the different color wires ... but I seem to remember you had your wiring harness replaced some years ago. With respect to the engine harness, it's all one big piece. That section goes from the alternator, behind the mounting bracket, up and over to bank 2 wiring picking up a few other sensors and then snaking back to the rear of the car.
Great find...hope that's the problem. Working on these cars I like to use the Occums Razor approach..... the simplest solution is usually the correct solution.
Seems like the only explanation given the single part number in the catalogue, but the wiring looked original with no splices. I guess the only way to find out is by looking at the wire colours at the main plug near the left hand rear strut. If it's original, it's a horrible choice of colours. Black is live. Different harness, Mitch. That was the main ECU harness.
Looking at your earlier picture showing the plug with a short length of loom and a broken wire, it does not look factory at all but very much like the 3-pin oval plug was inserted as a pigtail then sealed with a heat shrink tube and some glue ("potting compound"). Also, each of the 3 wires appear to have heat shrink tubes over them, to insulate the splices I believe. The pigtails come with various wire colours without much logic. Here's one Toyota pigtail having the same wire colours as in your case except that the middle wire is white, not red/black. The function of the pin having the black wire on the pigtail is "sensing" (the alternator output voltage) thus it is connected to the permanent +12V line somewhere. Image Unavailable, Please Login So, most likely, you have a Toyota alternator. My 348 came also with a non-original alternator (installed by the PO) having the same 3-pin oval plug spliced to the original wires. The 3-pin connectors for the Toyota alternators may plug-in at the back or at the side, depending on the type of the regulator used: Image Unavailable, Please Login ....................................... Image Unavailable, Please Login
Update: I couldn't find a way of trimming back the sheath/potting compound without damaging the wires. The harness was getting shorter and shorter until it was inaccessible. Looks like I'll be forced to change the harness. $A1000 for a new harness if they are still available from the factory. Currently trying to figure out how much of the car I'll have to dismantle.
Looks like an engine out job... I think the harness runs in the "V" and behind the cam belts. Image Unavailable, Please Login Nil stock at the factory. Ugh... Image Unavailable, Please Login
There are only a few wires in that branch. Don't spend $1000A, just make it yourself. Splice in new connectors and wires somewhere along the branch. If you are picky, you can even get the same wire colors.
