ASD fuse keeps blowing
 

I had to do my 4.7 litre timing gear the other week as the guides were all worn and the engine developed a pretty bad timing chain rattle. Anyway, I did the job, and being such a pain in the a#$e job I followed the workshop manual to the T and did everything as described, and then checked and double checked my work. On completion of the job, I started it up and had it running as I was topping up my cooling system. It was running really sweet for between 5 - 10 minutes, then the idle got rougher and rougher until finally it stalled. After this I could start it and it would operate under throttle, but as soon as I tried to let it idle it would die. Eventually I couldn't start it at all. I came to the conclusion that something had come adrift in the engine as the fuel injectors were pulsing and it had good ignition spark so I ripped the rocker covers back off. Sure enough, the cam timing was still fine, and could not work out why it wouldn't start. I tried to start car by pouring petrol down the throttle body and sure enough it started. OK, nothing wrong with the engine. I started at the beginning and checked my fuses and found the 30a ASD fuse had blown. After replacing it, it would restart, run for a few seconds and blow again. Upon checking the wiring diagrams, it turns out the ASD relay controls the fuel injectors, ignition coils and 02 sensors. Been through all the wiring and can not find any obvious shorts anywhere. Disconnected each injector and coil pack one by one and also the 02 sensors, yet the fuse blew every time. In the end I disconnected the TPS and low and behold the ASD fuse has stopped blowing. It will run, idle, and eventually cut out, but the fuse is no longer blowing. I removed the TPS and noticed that a previous technician had had the TPS apart, probably because they're worth $240 from Jeep. I've ordered a new one, but I'm not so sure that this is going to fix the problem. I've googled the problem and there seems to be plenty of people that have the same problem just after replacing they're engine, or doing major work like the timing chains or cylinder heads. Am just wondering if anybody else has had a similar problem and how it was resolved, and if any of the auto elecy's on the board have any clue.
Thanks. This job has really done my head in and made me wish I'd kept my Jimny

Cant help with same issue but tps sensor is just a potentiometer, 1 wire goes to 5v , 1 to output signal, 1 to earth.
Sensor is avail for a fraction of that price from ebay or rockauto.

Yes I know it's just a potentiometer and I've never seen one blow a fuse before, but I cant explain why it's no longer blowing the fuse. I'm pretty sure its not even in the circuit. I ordered one on ebay for $130 delivered

OMG i have an 03 Grand at work with the 4.7 ltr & it has the same damn problem Origional PCM had cooked of an internal curcuit so we replaced it & coded it to the VIN & everything came alive but wouldnt start,Hooked up the DRBIII & only codes it would give me was 2/1 02 sensor heater low & No Crank Angle signal at PCM , replaced both & cleared codes , all good for 5 minutes & she got rough idle & started to stall out , i let it code & all hell broke loose , ASD relay was opening & closing really fast & the injectors filled the cylinders with raw fuel , before i realised what was happening i had fuel dripping out the first collector onto the ground ;( , dropped pipes & drained , pulled plugs & sucked out most of the fuel , drained oil & refilled with new oil , these things are known for the engine harness rubbing through on the rear of each tappet cover ,& accross the transmission housing , so i pulled all the wiring details i could gather & started back probing & testing all the assosiated curcuit wires , so far i have repaired the CAS circuit & thought i had fixed the ASD but its still intermtantly shorting to ground so i have another rub/pinch to hunt down ,ill be back into it in the morning , heat soak is a major killer in these beasts , this one has 70k on it but the engine harness is as brittle as chalk , im going to see if a new harness is available , im going to totally remove this one tomorro as i cant get to the harness behind the heads & block with out dropping the GB there is stuff all room up there to do any kind of fix , so ill let you know what i find .

Yes, the wiring harness seems pretty brittle on mine too. I can't believe it's placed hard up between the firewall and the passenger side rocker cover. If there is a problem with it I'm betting that's where it would be. So far, I hav'nt found anything. Just out of curiosity can you let me know what a new harness is worth if you locate one?

ASD fuse keeps blowing
 

I just got off the floor from our parts department , a new complete engine harness is $2678.50 but jeeparts has a tested second Hand. one for $900 this loom is comming out and ill strip it down and see if its viable to repair or not ;)

Re: ASD fuse keeps blowing
 

For Sale . One jeep grand cherokee lol. Ain't gonna keep it for very long I don't think:(

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