Logo
FULL SITE MENU

How do I replace a circuit in my wiring harness?

1stboat

1stboat

Regular Contributor
I have a 1994 5.7 GIPMDA. My boat has been acting weird. I have, I believe to the troubleshooting in the manual, traced it down to an open tps circuit. I'm getting a code 21. According to the Seloc manual it is a result of an open circuit 417; the circuit that sends the signal to the ECM letting it know how open the throttle is. It is an orange wire with a black strip.

My question is how do I replace it? How do I get it out of the tps harness and out of the ecm connector? Do I have to unroll the entire wire loom and replace the wire? What tool should I get to get the wire out of the harnesses,spade and all? Also, where can I find an orange wire with a black stripe. I'd like to replace it with the same color wire in case the boat gets sold. I don't want the next owner to have a wrong colored wire that could lead him in the wrong direction when troubleshooting in case he has trouble with the same sensor/circuit.
 
kimcrwbr1 said:
Have you tested the wire for continuity. I will normally check the harness for shorts and for good circuits are the connectors clean and the pins all the way in when you put the connector together. Clean the connectors with electrical cleaner inspect the pins male and female use a little dielectric grease when putting the connectors together I use a small jewelers screwdriver to push the pins all the way in after you put the connector together. Make sure the wire is bad before you tear into the loop.
Click to expand...


Yes, I've tested for continuity; there is none. That is why the wire has to be replaced. The harness has not been taken apart in the five years I've had the boat so the pins on the harness and ECM connector are fine with no corrosion or damage.
 
Last edited:
kimcrwbr1 said:
http://www.ebay.com/itm/BRAND-NEW-T...Parts_Accessories&hash=item256ef36e37&vxp=mtr does this look like your TPS you can probably get one at the auto part store part number 3855184 normally the ecm provides around 5 volts to the sensor measure the volts out of the other two wires as you open the throttle one raises voltage and the other drops voltage in relation to the throttle position nice steady sweep on a analog VOM. if the needle jerks or dosent move the TPS is bad.
Click to expand...

The tps has been replace with a new one, still have the same issue.
 
The wiring harness has caused me more than jus this issue. It is almost 20 years old. The protective jacket has come off more than one wire. I've put electrical tape on more wires than I care to count. I'd like to replace the whole wiring harness, the one that connects all the sensors and switches to the ECM. The problem is that volvo list several different part numbers and I don't know which one to look for.

According to this site, http://www.volvopentastore.com/Engi...on_id.947285130--store_id.366--view_id.775676, the part number is 3850364.

Yet, according to this site, http://www.volvopentastore.com/Engine-Harness-And-Bracket/dm/cart_id.152853783--session_id.947285130--store_id.366--view_id.775675, the part number is 3856496 which replaced part number 3850466.
 
....the reason i suggested that, is that the wire that connects to the ecm can only have so much resistance. even if you replace the wire with a new splice, the resistance of the new wire and the splice, can cause erratic readings to the ecm.
 
crankbait said:
....the reason i suggested that, is that the wire that connects to the ecm can only have so much resistance. even if you replace the wire with a new splice, the resistance of the new wire and the splice, can cause erratic readings to the ecm.
Click to expand...


I'd like to replace the existing wire with with a whole new one from the tps to the ecm. After all, it is almost winter; I have more time to get this fixed than I do money. If I replace the bad wire with a good one of the same length and gauge, it shouldn't add any more resistance.

I'm just not sure how to get the pin out of the tps harness and the ecm connector without damaging anything. I have been doing some research and there is a company that you can send your harness to and they replace the damaged connectors for you. They work on mostly cars that have been in wrecks, but I figure a wiring harness is a wiring harness; boat or car. I plan on calling them at least anyway. It can't hurt. This is the link to their site: http://www.aeromotive.us
 
There are many pin removal tools available. Some images in the search link below.
http://www.bing.com/search?FORM=IE8SRC&q=pin+removal+tools+for+wire+harness&src=IE-SearchBox

I'm sure you can find tinned wire in orange. For the black tracer you could just paint it on with nail polish. Solder the pin end splices and shrink tube the open wire.
Run your new wire alongside the harness and use convoluted tube to contain it all. http://www.bing.com/search?q=convoluted+tubing&qs=AS&form=QBRE&pq=convoluted&sc=8-10&sp=4&sk=SS1AS2
 
just a quick suggestion. i don't know where you are checking for continuity in the circuit for the tps to the ecm, so place the throttle in "wide open", then check for continuity. the tps is like a rheostat and will be at zero resistance at idle, and full resistance at wot. if you are checking the circuit with the tps "inline", this would explain no continuity. (just thinking out loud brfore you start cutting wires.....)
 
1stboat said:
. . . I'm just not sure how to get the pin out of the tps harness and the ecm connector without damaging anything. . . .
Click to expand...

The pin has a tang that angles outwards. When the pin is inserted into the plastic connector body the tang catches the plastic.

The trick to removing the pin is finding the tang. Once you find it you can gently push it back with a tiny screwdriver and withdraw the pin. To reinstall the pin snap it back into its hole in the connector body.

Here is a picture of male and female connector pins. The tangs are visible.
http://www.smart-stuff.co.uk/ekmps/...ir-harness-sam-unit-pin-connectors-4117-p.jpg
 
daves69 said:
There are many pin removal tools available. Some images in the search link below. http://www.bing.com/search?FORM=IE8SRC&q=pin+removal+tools+for+wire+harness&src=IE-SearchBox DUH, don't know why I didn't think of that. I googled just about everything else. I'm sure you can find tinned wire in orange. For the black tracer you could just paint it on with nail polish. Solder the pin end splices and shrink tube the open wire. Run your new wire alongside the harness and use convoluted tube to contain it all. http://www.bing.com/search?q=convoluted+tubing&qs=AS&form=QBRE&pq=convoluted&sc=8-10&sp=4&sk=SS1AS2
Click to expand...
Very good point.
 
crankbait said:
just a quick suggestion. i don't know where you are checking for continuity in the circuit for the tps to the ecm, so place the throttle in "wide open", then check for continuity. the tps is like a rheostat and will be at zero resistance at idle, and full resistance at wot. if you are checking the circuit with the tps "inline", this would explain no continuity. (just thinking out loud brfore you start cutting wires.....)
Click to expand...
I did do the continuity test with the throttle set at idle, both with the key on and off. I'll try again with it at wide open. Still, my brain says continuity is continuity, doesn't hurt to try it the way you suggested though. I checked for continuity by disconnecting the tps and ecm wiring harness. I then placed one of my multimeter's tip on the orange/black wire on the disconnected tps harness end and the other one on the orange/black wire of the disconnected ecm connector end. In other words, I check for continuity of the orange/black wire from harness to harness. Which, according to the wiring schematics should be one solid piece of wire.
 
Last edited:
ebacon said:
The pin has a tang that angles outwards. When the pin is inserted into the plastic connector body the tang catches the plastic. The trick to removing the pin is finding the tang. Once you find it you can gently push it back with a tiny screwdriver and withdraw the pin. To reinstall the pin snap it back into its hole in the connector body. Here is a picture of male and female connector pins. The tangs are visible. http://www.smart-stuff.co.uk/ekmps/...ir-harness-sam-unit-pin-connectors-4117-p.jpg
Click to expand...
Keep and eye out for the tang, got it.
 
.......again, try doing the test with the throttle at "wot". the tps can be acting as a in line switch that completes the circuit. if there are still no results..... connect one test lead to your wire , and one to ground.......then move your throttle lever open and closed, any see if you you get a reading.

if things are still dead....switch your meter to low voltage setting.....connect the positive lead to the suspect wire, and the other lead the engine ground.......turn key to "on/run"......and move the throttle forward and back. see if you get a reading...

if things are still dead....see if you have voltage going to the engine side of the tps.
 
Back
Top